audio: replace profiles with direct sample rate + buffer size controls

- Removed audio profile grid and preset cards
- Added two dropdowns: Sample Rate (44.1/48/96/192 kHz) and Buffer
  Size (64-2048 frames)
- New loadAudioParams() reads current rate+period from API
- New setAudioParams() POSTs {period, rate} directly on change
- Cleaned up unused CSS (.audio-profile-grid, .ap-card, .ap-key, etc.)
- Removed unused audioProfiles variable

src/web/ui-v2-dist/index.html

@@ -137,14 +137,6 @@ body{display:flex;flex-direction:column;max-height:100vh;user-select:none;-webki
 .wifi-connect-pw input{flex:1;padding:6px 8px;border-radius:6px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-family:var(--font);font-size:11px;outline:none;min-height:36px}
 .wifi-connect-pw input:focus{border-color:var(--amber)}
 .wifi-connect-pw button{min-width:52px;min-height:36px;border-radius:6px;border:1px solid var(--amber);background:var(--amber);color:#000;font-family:var(--font);font-size:11px;font-weight:700;cursor:pointer}
-.audio-profile-grid{display:grid;grid-template-columns:1fr 1fr;gap:4px}
-.ap-card{background:var(--surface);border:1px solid var(--border);border-radius:6px;padding:4px 6px;cursor:pointer;transition:all .12s;text-align:center}
-.ap-card:active{transform:scale(.95)}
-.ap-card.active{border-color:var(--amber);background:rgba(232,160,48,.08)}
-.ap-card .ap-key{font-size:9px;font-weight:600;text-transform:capitalize;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
-.ap-card .ap-desc{font-size:8px;color:var(--text2)}
-.ap-card.loading{opacity:.5;pointer-events:none}
-.ap-card.loading .ap-key::after{content:' ⟳';animation:spin .6s linear infinite;display:inline-block}
 
 /* Loading overlay */
 .loading-overlay{position:fixed;inset:0;background:rgba(0,0,0,.5);z-index:300;display:flex;align-items:center;justify-content:center;flex-direction:column;gap:8px}
@@ -268,8 +260,24 @@ body{display:flex;flex-direction:column;max-height:100vh;user-select:none;-webki
       <div class="setting-row"><span class="sr-label">🔥 Hotspot</span><span class="sr-value" id="hotspotStatus">Off</span><button class="sr-action" id="hotspotToggle">Enable</button></div>
     </div>
     <div class="setting-group" id="section-audio"><div class="setting-group-title">Audio</div>
-      <div class="setting-row"><span class="sr-label">🎛 Profile</span><span class="sr-value" id="audioProfileLabel">—</span></div>
-      <div class="audio-profile-grid" id="audioProfileGrid"></div>
+      <div class="setting-row"><span class="sr-label">🎛 Sample Rate</span>
+        <select id="audioSampleRate" onchange="setAudioParams()" style="flex:1;max-width:140px;font-size:11px;padding:4px 8px;min-height:34px;border-radius:6px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-family:var(--font)">
+          <option value="44100">44.1 kHz</option>
+          <option value="48000" selected>48 kHz</option>
+          <option value="96000">96 kHz</option>
+          <option value="192000">192 kHz</option>
+        </select>
+      </div>
+      <div class="setting-row"><span class="sr-label">📦 Buffer Size</span>
+        <select id="audioBufferSize" onchange="setAudioParams()" style="flex:1;max-width:140px;font-size:11px;padding:4px 8px;min-height:34px;border-radius:6px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-family:var(--font)">
+          <option value="64">64</option>
+          <option value="128">128</option>
+          <option value="256" selected>256</option>
+          <option value="512">512</option>
+          <option value="1024">1024</option>
+          <option value="2048">2048</option>
+        </select>
+      </div>
       <div class="setting-row"><span class="sr-label">🎸 Instrument</span><span class="sr-value" id="instrumentLabel">Guitar</span><button class="sr-action" id="instrumentCycleBtn" style="min-width:44px;padding:4px 10px">Cycle</button></div>
       <div class="setting-row"><span class="sr-label">🔄 Channel Mode</span><span class="sr-value" id="channelModeLabel">Dual Mono</span><button class="sr-action" id="channelModeToggle">Toggle</button></div>
       <div class="setting-row"><span class="sr-label">🔗 Routing</span><span class="sr-value" id="routingModeLabel">4CM</span><button class="sr-action" id="routingModeToggle">Toggle</button></div>
@@ -379,7 +387,11 @@ const API = {
   btMidiDisable:()=>API._fetch('/api/bluetooth/midi-disable',{method:'POST'}),
   btDiscoverableSet:(on)=>API._fetch('/api/bluetooth/discoverable',{method:'POST',body:JSON.stringify({on})}),
   listAudioProfiles:()=>API._fetch('/api/audio/profiles'),
-  setAudioProfile:(p)=>API._fetch('/api/audio/profile',{method:'POST',body:JSON.stringify({profile:p})}),
+  getAudioProfile:()=>API._fetch('/api/audio/profile'),
+  setAudioProfile:(p)=>{
+    if(typeof p==='string') return API._fetch('/api/audio/profile',{method:'POST',body:JSON.stringify({profile:p})});
+    return API._fetch('/api/audio/profile',{method:'POST',body:JSON.stringify(p)});
+  },
   getChannelMode:()=>API._fetch('/api/channel-mode'),
   setChannelMode:(m)=>API._fetch('/api/channel-mode',{method:'POST',body:JSON.stringify({channel_mode:m})}),
   getRouting:(ch)=>API._fetch('/api/routing?channel='+(ch||'guitar')),
@@ -404,7 +416,6 @@ let currentChannel='guitar';
 let channels=['guitar','bass','keys','vocals','backing_tracks'];
 let presets=[];
 let snapshots={};
-let audioProfiles=[];
 let currentBank=0;
 let pollTimer=null;
 let tunerPollTimer=null;
@@ -671,27 +682,13 @@ async function loadSystemInfo(){
   }catch(e){}
 }
 
-async function loadAudioProfiles(){
+async function loadAudioParams(){
   try{
-    audioProfiles=await API.listAudioProfiles();
-    const grid=document.getElementById('audioProfileGrid');
-    const cp=audioProfiles.current||'standard';
-    grid.innerHTML='';
-    (audioProfiles.profiles||[]).forEach(p=>{
-      const d=document.createElement('div');
-      d.className='ap-card'+(p.key===cp?' active':'');
-      d.innerHTML='<div class="ap-key">'+p.key.replace(/_/g,' ')+'</div><div class="ap-desc">'+p.period+'fr / '+p.rate+'Hz</div>'+((p.key===cp)?'<div style="font-size:8px;color:var(--amber)">● Active</div>':'');
-      d.onclick=async()=>{
-        d.classList.add('loading');
-        try{
-          await API.setAudioProfile(p.key);
-          toast('Profile: '+p.key);
-          loadAudioProfiles();
-        }catch(e){toast(e.message);d.classList.remove('loading');}
-      };
-      grid.appendChild(d);
-    });
-    document.getElementById('audioProfileLabel').textContent=cp;
+    const p=await API.getAudioProfile();
+    const rate=p.rate||48000;
+    const period=p.period||256;
+    document.getElementById('audioSampleRate').value=String(rate);
+    document.getElementById('audioBufferSize').value=String(period);
     const cm=await API.getChannelMode();
     if(cm.channel_mode)document.getElementById('channelModeLabel').textContent=cm.channel_mode.replace(/-/g,' ').replace(/\b\w/g,l=>l.toUpperCase());
     const rt=await API.getRouting(currentChannel);
@@ -699,6 +696,18 @@ async function loadAudioProfiles(){
   }catch(e){}
 }
 
+async function setAudioParams(){
+  const rate=parseInt(document.getElementById('audioSampleRate').value);
+  const period=parseInt(document.getElementById('audioBufferSize').value);
+  const btn=document.querySelector('.sn-btn[data-section="audio"]');
+  if(btn)btn.textContent='⏳ Applying...';
+  try{
+    await API.setAudioProfile({period,rate});
+    toast('Audio: '+rate+'Hz / '+period+'fr');
+  }catch(e){toast('Failed: '+e.message);}
+  if(btn)btn.textContent='🎛 Audio';
+}
+
 async function loadBtStatus(){
   try{
     const st=await API.btStatus();
@@ -809,7 +818,7 @@ function init(){
     btn.onclick=()=>{
       const view=btn.dataset.view;
       if(view==='main'){document.querySelectorAll('.tab-btn').forEach(b=>b.classList.remove('active'));btn.classList.add('active');}
-      else if(view==='settings'){openOverlay('Settings');loadNetworkInfo();loadSystemInfo();loadAudioProfiles();loadHotspotStatus();loadBtStatus();loadBtMidi();return;}
+      else if(view==='settings'){openOverlay('Settings');loadNetworkInfo();loadSystemInfo();loadAudioParams();loadHotspotStatus();loadBtStatus();loadBtMidi();return;}
       else if(view==='presets'){openOverlay('Presets');loadPresets();}
       else if(view==='snapshots'){openOverlay('Snapshots');loadSnapshots();}
       else if(view==='downloads')openOverlay('Downloads');
@@ -821,7 +830,7 @@ function init(){
     openOverlay('Settings');
     loadNetworkInfo();
     loadSystemInfo();
-    loadAudioProfiles();
+    loadAudioParams();
     loadHotspotStatus();
     loadBtStatus();
     loadBtMidi();
@@ -844,11 +853,11 @@ function init(){
   document.getElementById('channelModeToggle').onclick=async()=>{
     const cur=document.getElementById('channelModeLabel').textContent.toLowerCase();
     const next=cur.includes('dual')?'stereo':'dual-mono';
-    try{await API.setChannelMode(next);loadAudioProfiles();toast('Mode: '+next);}catch(e){toast(e.message);}
+    try{await API.setChannelMode(next);loadAudioParams();toast('Mode: '+next);}catch(e){toast(e.message);}
   };
   document.getElementById('routingModeToggle').onclick=async()=>{
     const cur=document.getElementById('routingModeLabel').textContent;
-    try{await API.setRouting(currentChannel,{routing_mode:cur==='MONO'?'4cm':'mono'});loadAudioProfiles();}catch(e){toast(e.message);}
+    try{await API.setRouting(currentChannel,{routing_mode:cur==='MONO'?'4cm':'mono'});loadAudioParams();}catch(e){toast(e.message);}
   };
   document.getElementById('netModeToggle').onclick=async()=>{
     const lbl=document.getElementById('netDhcpStatus');
@@ -883,7 +892,7 @@ function init(){
       await API.saveSettings({channel_mode:'dual-mono',brightness:8,tap_tempo:120});
       await API.setRouting(currentChannel,{routing_mode:'mono'}).catch(()=>{});
       toast('Defaults restored');
-      setTimeout(()=>{closeOverlay('Settings');loadAudioProfiles();},1000);
+      setTimeout(()=>{closeOverlay('Settings');loadAudioParams();},1000);
     }catch(e){toast('Failed: '+e.message);}
   };
   document.getElementById('btnRestartSvc').onclick=()=>{toast('Restarting service...');fetch('/api/settings',{method:'POST',body:JSON.stringify({_restart:true})}).catch(()=>{});};