feat: Add threaded review comments + agent comment responses

Introduces GitHub-style threaded comments via parentCommentId self-reference.
Users and agents can reply within comment threads, and review agents receive
comment IDs so they can post targeted responses via comment-responses.json.

- Migration 0032: parentCommentId column + index on review_comments
- Repository: createReply() copies parent context, default author 'you' → 'user'
- tRPC: replyToReviewComment procedure, requestPhaseChanges passes threaded comments
- Orchestrator: formats [comment:ID] tags with full reply threads in task description
- Agent IO: readCommentResponses() reads .cw/output/comment-responses.json
- OutputHandler: processes agent comment responses (creates replies, resolves threads)
- Execute prompt: conditional <review_comments> block when task has [comment:] markers
- Frontend: CommentThread renders root+replies with agent-specific styling + reply form
- Sidebar/ReviewTab: root-only comment counts, reply mutation plumbing through DiffViewer chain

apps/server/container.ts

@@ -183,6 +183,7 @@ export async function createContainer(options?: ContainerOptions): Promise<Conta
     options?.debug ?? false,
     undefined, // processManagerOverride
     repos.chatSessionRepository,
+    repos.reviewCommentRepository,
   );
   log.info('agent manager created');