feat: show quota error in status bar instead of toast

Toast approach was unreliable due to Gradio's iframe/document context.
Instead write the error directly into the wf_statusbar_<slot_id> span
which is always in our own DOM. Text turns red with the full ZeroGPU
quota message, then resets to normal after 15s so user can retry.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -1843,7 +1843,7 @@ def _build_waveform_html(audio_path: str, segments: list, slot_id: str,
             scrolling="no"></iframe>
   </div>
   <div style="display:flex;align-items:center;gap:8px;margin-top:6px;">
-    <span style="color:#888;font-size:11px;">Click a segment to regenerate &nbsp;|&nbsp; Playhead syncs to video</span>
+    <span id="wf_statusbar_{slot_id}" style="color:#888;font-size:11px;">Click a segment to regenerate &nbsp;|&nbsp; Playhead syncs to video</span>
     <a href="{audio_url}" download="audio_{slot_id}.wav"
        style="margin-left:auto;background:#333;color:#eee;border:1px solid #555;
               border-radius:4px;padding:3px 10px;font-size:12px;text-decoration:none;">
@@ -2109,7 +2109,8 @@ _GLOBAL_JS = """
     }).catch(function(e) {
       console.error('[fireRegen] fetch error:', e);
       if (lbl) lbl.textContent = 'Error — see console';
-      _showRegenToast('Request failed: ' + e.message, true);
+      var sb = document.getElementById('wf_statusbar_' + slot_id);
+      if (sb) { sb.style.color = '#e05252'; sb.textContent = '⚠ Request failed: ' + e.message; }
     });
   }
 
@@ -2206,9 +2207,19 @@ _GLOBAL_JS = """
           var lbl = document.getElementById('wf_seglabel_' + slot_id);
 
           if (hadError) {
-            // Show toast with the full error message (includes quota countdown)
             var toastMsg = typeof errMsg === 'string' ? errMsg : JSON.stringify(errMsg);
-            _showRegenToast('⚠ ' + toastMsg, true);
+
+            // Show error in the status bar (always in our DOM, no cross-origin issues)
+            var statusBar = document.getElementById('wf_statusbar_' + slot_id);
+            if (statusBar) {
+              statusBar.style.color = '#e05252';
+              statusBar.textContent = '⚠ ' + toastMsg;
+              // Reset after 15s so user can try again
+              setTimeout(function() {
+                statusBar.style.color = '#888';
+                statusBar.textContent = 'Click a segment to regenerate \u00a0|\u00a0 Playhead syncs to video';
+              }, 15000);
+            }
 
             // Restore waveform HTML to pre-regen snapshot
             if (preRegenWaveHtml !== null) {
@@ -2225,7 +2236,7 @@ _GLOBAL_JS = """
               }
             }
 
-            if (lbl) lbl.textContent = 'Regen failed — quota exceeded';
+            if (lbl) lbl.textContent = 'Regen failed';
           } else {
             if (lbl) lbl.textContent = 'Done';