feat: add My GPS button to asset detail GPS editor

Adds a '📍 My GPS' button to the GPS Map Editor card in the asset
detail screen that:
- Grabs device GPS via navigator.geolocation.getCurrentPosition
- Places map marker at current device position
- Auto-unlocks the GPS editor if locked, shows Save button
- Displays accuracy in status text
- Provides clear error messages for denied/timed-out/unavailable

Includes enableHighAccuracy: true, 15s timeout, 60s cache.

static/index.html

@@ -1303,6 +1303,7 @@
         <div id="detailGpsInfo" style="font-size:12px;color:var(--text2);margin-bottom:6px;"></div>
         <div id="detailGpsMap" style="height:300px;border-radius:8px;margin-bottom:8px;border:1px solid var(--border);"></div>
         <div style="display:flex;gap:8px;align-items:center;flex-wrap:wrap;">
+          <button id="detailGpsMyGpsBtn" class="btn btn-outline btn-sm" onclick="getCurrentGps()" title="Get device GPS coordinates"><svg class="gi" aria-hidden="true"><use href="#gi-bullseye"/></svg> My GPS</button>
           <button id="detailGpsSaveBtn" class="btn btn-green btn-sm" onclick="saveGpsCoords()" style="display:none;"><svg class="gi" aria-hidden="true"><use href="#gi-save"/></svg> Save GPS</button>
           <span id="detailGpsCoords" style="font-size:12px;color:var(--text2);font-family:monospace;"></span>
           <span id="detailGpsStatus" style="font-size:11px;color:var(--text3);"></span>
@@ -4280,6 +4281,69 @@
       }
     }
 
+    async function getCurrentGps() {
+      // Check browser geolocation support
+      if (!navigator.geolocation) {
+        showToast('GPS not supported on this device', true);
+        return;
+      }
+
+      const myGpsBtn = document.getElementById('detailGpsMyGpsBtn');
+      myGpsBtn.textContent = '⏳ Getting GPS...';
+      myGpsBtn.disabled = true;
+
+      navigator.geolocation.getCurrentPosition(
+        function(pos) {
+          const lat = Math.round(pos.coords.latitude * 1000000) / 1000000;
+          const lng = Math.round(pos.coords.longitude * 1000000) / 1000000;
+
+          // Update the marker on the GPS editor map
+          if (_gpsState.marker) {
+            _gpsState.marker.setLatLng([lat, lng]);
+          } else {
+            showToast('GPS map not initialized yet', true);
+            myGpsBtn.textContent = '📍 My GPS';
+            myGpsBtn.disabled = false;
+            return;
+          }
+
+          // Update coords display
+          document.getElementById('detailGpsCoords').textContent =
+            `${lat.toFixed(6)}, ${lng.toFixed(6)}`;
+
+          // Auto-unlock if currently locked
+          if (!_gpsState.unlocked) {
+            toggleGpsLock();
+          }
+
+          // Show save button and update status/info
+          document.getElementById('detailGpsSaveBtn').style.display = '';
+          document.getElementById('detailGpsStatus').textContent =
+            `📍 Device GPS (accuracy: ${Math.round(pos.coords.accuracy)}m)`;
+
+          showToast(`📍 GPS position set: ${lat}, ${lng}`, false);
+
+          myGpsBtn.textContent = '📍 My GPS';
+          myGpsBtn.disabled = false;
+        },
+        function(err) {
+          const msgs = {
+            1: 'GPS permission denied — allow location access in your browser settings',
+            2: 'GPS position unavailable — try moving to an open area',
+            3: 'GPS request timed out — try again',
+          };
+          showToast('GPS error: ' + (msgs[err.code] || err.message), true);
+          myGpsBtn.textContent = '📍 My GPS';
+          myGpsBtn.disabled = false;
+        },
+        {
+          enableHighAccuracy: true,
+          timeout: 15000,
+          maximumAge: 60000,
+        }
+      );
+    }
+
     function statusBadge(status) {
       return '';
     }