perf(app): better memory management

specs/13-speech-recognition-timeout-cleanup.md

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+## Speech recognition timeout cleanup
+
+Stop stray restart timers from keeping recognition alive
+
+---
+
+### Summary
+
+`packages/app/src/utils/speech.ts` schedules 150ms `setTimeout` restarts in `recognition.onerror` and `recognition.onend` when `shouldContinue` is true. These timers are not tracked or cleared, so they can fire after `stop()`/cleanup and call `recognition.start()`, keeping recognition + closures alive unexpectedly.
+
+This spec tracks restart timers explicitly and clears them on stop/cleanup.
+
+---
+
+### Scoped files (parallel-safe)
+
+- `packages/app/src/utils/speech.ts`
+
+---
+
+### Goals
+
+- Ensure no restart timers remain scheduled after `stop()` or `onCleanup`
+- Prevent `recognition.start()` from being called after cleanup
+- Keep behavior identical in the normal recording flow
+
+---
+
+### Non-goals
+
+- Changing the recognition UX/state machine beyond timer tracking
+
+---
+
+### Proposed approach
+
+- Add `let restartTimer: number | undefined`.
+- Add helpers:
+  - `clearRestart()`
+  - `scheduleRestart()` (guards `shouldContinue` + `recognition`)
+- Replace both raw `setTimeout(..., 150)` uses with `window.setTimeout` stored in `restartTimer`.
+- Call `clearRestart()` in:
+  - `start()`
+  - `stop()`
+  - `onCleanup(...)`
+  - `recognition.onstart` (reset state)
+  - any path that exits recording due to error
+
+---
+
+### Implementation steps
+
+1. Introduce `restartTimer` and helpers
+
+2. Replace `setTimeout(() => recognition?.start(), 150)` occurrences
+
+3. Clear the timer in all stop/cleanup paths
+
+---
+
+### Acceptance criteria
+
+- After calling `stop()` or disposing the creator, there are no delayed restarts
+- No unexpected `recognition.start()` calls occur after recording is stopped
+
+---
+
+### Validation plan
+
+- Manual:
+  - Start/stop recording repeatedly
+  - Trigger a `no-speech` error and confirm restarts only happen while recording is active
+  - Navigate away/unmount the component using `createSpeechRecognition` and confirm no restarts happen afterward