Improve import UX: progress overlay, pyannote fix, debug logging

- Enhanced ProgressOverlay with spinner, better styling, and z-index 9999
- Import button shows "Processing..." with pulse animation while transcribing
- Fix pyannote API: use token= instead of deprecated use_auth_token=
- Read HF_TOKEN from environment for pyannote model download
- Add console logging for click-to-seek debugging
- Add color-scheme: dark for native form controls

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

src/routes/+page.svelte

@@ -68,6 +68,7 @@
   const speakerColors = ['#e94560', '#4ecdc4', '#ffe66d', '#a8e6cf', '#ff8b94', '#c7ceea', '#ffd93d', '#6bcb77'];
 
   function handleWordClick(timeMs: number) {
+    console.log('[voice-to-notes] Word clicked, seeking to', timeMs, 'ms');
     waveformPlayer?.seekTo(timeMs);
   }
 
@@ -232,8 +233,12 @@
 <div class="app-header">
   <h1>Voice to Notes</h1>
   <div class="header-actions">
-    <button class="import-btn" onclick={handleFileImport}>
-      Import Audio/Video
+    <button class="import-btn" onclick={handleFileImport} disabled={isTranscribing}>
+      {#if isTranscribing}
+        Processing...
+      {:else}
+        Import Audio/Video
+      {/if}
     </button>
     <button class="settings-btn" onclick={() => showSettings = true} title="Settings">
       Settings
@@ -303,9 +308,18 @@
     font-size: 0.875rem;
     font-weight: 500;
   }
-  .import-btn:hover {
+  .import-btn:hover:not(:disabled) {
     background: #d63851;
   }
+  .import-btn:disabled {
+    opacity: 0.7;
+    cursor: not-allowed;
+    animation: pulse 1.5s ease-in-out infinite;
+  }
+  @keyframes pulse {
+    0%, 100% { opacity: 0.7; }
+    50% { opacity: 1; }
+  }
   .header-actions {
     display: flex;
     gap: 0.5rem;