fix: guard stopManualPhoto() call — mode switching threw ReferenceError

setAddAssetMode() called stopManualPhoto() which was removed during
the canvas→file-input refactor. Every mode switch failed silently.

static/index.html

@@ -809,7 +809,7 @@
        ═══════════════════════════════════════════════════════════════════════ -->
   <div id="tabAddAsset" class="tab-panel active">
     <!-- Hidden photo picker input -->
-    <input type="file" id="photoPicker" accept="image/*" capture="environment" style="display:none;" onchange="handlePickedPhoto(event)">
+    <input type="file" id="photoPicker" accept="image/*" style="display:none;">
     <!-- Mode Toggles -->
     <div class="mode-toggles">
       <button class="mode-toggle active" data-mode="barcode" onclick="setAddAssetMode('barcode')">📷 Barcode</button>
@@ -1693,7 +1693,7 @@
       // Stop any running scanners
       stopScanning();
       stopOcrCamera();
-      stopManualPhoto();
+      if (typeof stopManualPhoto === 'function') stopManualPhoto();
 
       if (mode === 'barcode') {
         startScanning();