feat: add Clear GPS card to Dashboard page

static/index.html

@@ -1049,6 +1049,17 @@
         <button class="btn btn-sm btn-outline" onclick="switchPage('activity')">View Full Log →</button>
       </div>
     </div>
+    <div class="card">
+      <div class="card-title">📍 Clear Asset GPS</div>
+      <p style="font-size:13px;color:var(--text2);margin-bottom:10px;">
+        Clear GPS coordinates from an asset. Enter the asset ID or machine ID.
+      </p>
+      <div style="display:flex;gap:8px;margin-bottom:10px;">
+        <input id="clearGpsAssetId" type="text" class="input-field" placeholder="Asset ID or Machine ID" style="flex:1;">
+        <button class="btn btn-outline btn-sm" onclick="clearAssetGps()">📍 Clear GPS</button>
+      </div>
+      <div id="clearGpsResult" style="display:none;"></div>
+    </div>
   </div>
 
   <!-- ── SETTINGS ── -->