feat: Fix progress bar hanging and improve UI responsiveness during indexing

Adds strategic yield points and direct stdout writes to prevent progress animation from freezing when the main thread is blocked by synchronous operations. Introduces 'finalizing' phase to smooth transition between parsing and resolving steps, ensuring progress reaches 100% completion.

src/extraction/index.ts

@@ -51,7 +51,7 @@ const WORKER_RECYCLE_INTERVAL = 250;
  * Progress callback for indexing operations
  */
 export interface IndexProgress {
-  phase: 'scanning' | 'parsing' | 'storing' | 'resolving';
+  phase: 'scanning' | 'parsing' | 'storing' | 'finalizing' | 'resolving';
   current: number;
   total: number;
   currentFile?: string;
@@ -460,6 +460,16 @@ export class ExtractionOrchestrator {
     const total = files.length;
     let processed = 0;
 
+    // Emit parsing phase immediately so the progress bar appears during worker setup.
+    // The yield lets the shimmer worker flush the phase transition to stdout before
+    // the main thread starts synchronous grammar detection work.
+    onProgress?.({
+      phase: 'parsing',
+      current: 0,
+      total,
+    });
+    await new Promise(resolve => setImmediate(resolve));
+
     // Detect needed languages and load grammars in the parse worker
     const neededLanguages = [...new Set(files.map((f) => detectLanguage(f)))];
 
@@ -719,6 +729,18 @@ export class ExtractionOrchestrator {
       }
     }
 
+    // Report 100% so the progress bar doesn't hang at 99%
+    onProgress?.({
+      phase: 'parsing',
+      current: total,
+      total,
+    });
+
+    // Yield so the shimmer worker's buffered stdout writes can flush.
+    // Worker thread stdout is proxied through the main thread's event loop,
+    // so synchronous work here blocks the animation from rendering.
+    await new Promise(resolve => setImmediate(resolve));
+
     // Retry pass: files that failed due to WASM memory corruption may succeed
     // on a fresh worker with a clean heap. Recycle before each attempt so
     // every file gets the absolute cleanest WASM state possible.