Auto-reply refactor notes (2025-11-26)

Split src/auto-reply/reply.ts into smaller helpers:
- Command handling lives in src/auto-reply/command-reply.ts.
- Audio transcription helpers live in src/auto-reply/transcription.ts.
- Shared reply types live in src/auto-reply/types.ts (re-exported from reply.ts).
runCommandReply now returns { payload, meta }, supports injected enqueue runners for tests, logs structured metadata, and respects mediaMaxMb for local media paths.
Added focused tests:
- src/auto-reply/command-reply.test.ts exercises Claude flag injection, session args, timeout messaging, media token handling, and Claude metadata reporting.
- src/auto-reply/transcription.test.ts covers media download + transcription command invocation.
Existing public surface (getReplyFromConfig, autoReplyIfConfigured, ReplyPayload) remains unchanged; integration tests still pass (pnpm test).