feat: add progress bar to init/reinit with per-file tracking

- processFiles() now accepts onProgress callback (completed, total, currentFile)
- InitOptions.onProgress receives structured ProgressInfo object
- initProject aggregates progress across all directories
- CLI renders ASCII progress bar: [████░░░░░░] 3/20 | filename.ts
- Pi extension sends structured updates with percentage + file details
- All 52 tests passing

pi-extension.ts

@@ -82,7 +82,13 @@ export default function (pi: ExtensionAPI) {
 					verbose: false,
 					llmClient: client,
 					cacheDir: ctx.cwd,
-					onProgress: (msg) => _onUpdate?.({ content: [{ type: "text", text: msg }] }),
+					onProgress: (info) => {
+						const pct = info.total > 0 ? Math.round((info.completed / info.total) * 100) : 0;
+						_onUpdate?.({
+							content: [{ type: "text", text: `${info.message} (${pct}%)` }],
+							details: { progress: pct, file: info.currentFile, dir: info.dir },
+						});
+					},
 				});
 				return {
 					content: [
@@ -208,7 +214,13 @@ export default function (pi: ExtensionAPI) {
 					verbose: false,
 					llmClient: client,
 					cacheDir: ctx.cwd,
-					onProgress: (msg) => _onUpdate?.({ content: [{ type: "text", text: msg }] }),
+					onProgress: (info) => {
+						const pct = info.total > 0 ? Math.round((info.completed / info.total) * 100) : 0;
+						_onUpdate?.({
+							content: [{ type: "text", text: `${info.message} (${pct}%)` }],
+							details: { progress: pct, file: info.currentFile, dir: info.dir },
+						});
+					},
 				});
 				return {
 					content: [