Add clear asset GPS endpoint + UI

- DELETE /api/assets/{id}/gps: clears lat/lng to NULL
- GET /api/assets/{id}: asset lookup by ID
- GET /api/assets/search?machine_id=: asset lookup by machine ID
- Export & Admin page: Clear Asset GPS card with lookup + confirmation
- Tests: 204 success + 404 not found

static/index.html

@@ -878,6 +878,17 @@
         <a href="/api/export/checkins" class="btn btn-outline" download>📄 Export Check-Ins CSV</a>
       </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 class="card">
       <div class="card-title">Database</div>
       <div style="display:flex;flex-wrap:wrap;gap:8px;">
@@ -2110,6 +2121,58 @@ async function confirmResetDb() {
   }
 }
 
+// ── Clear Asset GPS ──────────────────────────────────────────────────────
+async function clearAssetGps() {
+  const input = document.getElementById('clearGpsAssetId').value.trim();
+  if (!input) {
+    showToast('Enter an asset ID or machine ID', true);
+    return;
+  }
+  const resultEl = document.getElementById('clearGpsResult');
+  resultEl.style.display = 'none';
+
+  try {
+    // Try numeric asset ID first, otherwise search by machine_id
+    let asset;
+    const idNum = parseInt(input);
+    if (!isNaN(idNum) && idNum > 0) {
+      try {
+        asset = await api('/api/assets/' + idNum);
+      } catch (e) {
+        // Fall through to machine_id search
+      }
+    }
+    if (!asset) {
+      asset = await api('/api/assets/search?machine_id=' + encodeURIComponent(input));
+    }
+
+    if (!asset || !asset.id) {
+      resultEl.style.display = '';
+      resultEl.innerHTML = '<span style="color:var(--red);">Asset not found</span>';
+      return;
+    }
+
+    const confirmed = await showModal(
+      'Clear GPS Data',
+      `<strong>${esc(asset.name)}</strong> (#${asset.id})<br>
+       Machine ID: ${esc(asset.machine_id)}<br>
+       Current: lat=${asset.latitude || 'none'}, lng=${asset.longitude || 'none'}<br><br>
+       Remove GPS coordinates from this asset?`,
+      'Clear GPS', 'btn-danger'
+    );
+    if (!confirmed) return;
+
+    await api('/api/assets/' + asset.id + '/gps', { method: 'DELETE' });
+    resultEl.style.display = '';
+    resultEl.innerHTML = '<span style="color:var(--green);">✅ GPS data cleared for ' + esc(asset.name) + ' (#' + asset.id + ')</span>';
+    document.getElementById('clearGpsAssetId').value = '';
+    showToast('GPS data cleared');
+  } catch (e) {
+    resultEl.style.display = '';
+    resultEl.innerHTML = '<span style="color:var(--red);">' + esc(e.message) + '</span>';
+  }
+}
+
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