fix(coding-agent): fixed memory leak by cancelling idle compaction

- Fixed memory leak by cancelling idle compaction timer on event controller disposal.
- Fixed session resumption to preserve last non-empty session when starting fresh.
- Fixed stash detection to use git ref resolution instead of output parsing for reliability.
- Fixed secret obfuscation to deobfuscate restored session messages locally while keeping LLM messages obfuscated.
- Fixed stash pop operation to preserve staged changes with --index flag after task branch merges.
- Changed idle compaction settings from enum to numeric type for flexible configuration.

packages/coding-agent/src/modes/controllers/event-controller.ts

@@ -25,6 +25,10 @@ export class EventController {
 	#idleCompactionTimer?: NodeJS.Timeout;
 	constructor(private ctx: InteractiveModeContext) {}
 
+	dispose(): void {
+		this.#cancelIdleCompaction();
+	}
+
 	#resetReadGroup(): void {
 		this.#lastReadGroup = undefined;
 	}
@@ -607,6 +611,7 @@ export class EventController {
 			if (this.#currentContextTokens() < threshold) return;
 			void this.ctx.session.runIdleCompaction();
 		}, timeoutMs);
+		this.#idleCompactionTimer.unref?.();
 	}
 
 	#currentContextTokens(): number {