Improve code documentation and maintainer notes

- Add a top-level doc comment to useStreamingGeneration.ts and document the streaming lifecycle.
- Add docstrings to helper functions in useStreamingGeneration.ts.
- Add section comments to web/app/page.tsx around reducer state, server health polling, and generation handling.
- Add file-level comments to API proxy routes explaining the security architecture.
- Add a file map / maintainer guide comment to server/vibevoice_server.py.
- Add docstrings for key internal helpers in server/vibevoice_server.py.
- Document environment variables used by the server in server/vibevoice_server.py.
- Add comments identifying VibePod-specific patches around VibeVoice internals.
- Format server/vibevoice_server.py with black.

Co-authored-by: LyAhn <27559362+LyAhn@users.noreply.github.com>

web/app/page.tsx

@@ -24,6 +24,8 @@ export interface ServerConfig {
   default_inference_steps: number;
 }
 
+// --- State Management ---
+
 interface AppState {
   script: string;
   speaker: string;
@@ -199,6 +201,8 @@ export default function HomePage() {
     resumeThresholdSecs: state.resumeThresholdSecs,
   });
 
+  // --- Server Health & Status Polling ---
+
   // Server health polling — fast while not ready, slow when online
   useEffect(() => {
     let timeoutId: ReturnType<typeof setTimeout>;
@@ -246,6 +250,8 @@ export default function HomePage() {
     };
   }, []);
 
+  // --- Generation Handling ---
+
   const handleGenerate = useCallback(async () => {
     if (!state.script.trim() || state.isGenerating) return;
     addLog(`${wordCount} words queued`);