feat(lifecycle): replace progress comment with PR created message

[aaight]

Summary

• Threads progressCommentId through the execution pipeline: ProgressMonitor → AgentResult → adapter → agent-execution → lifecycle
• Updates progress comment — When the implementation agent posts "PR created: …", handleSuccess now calls updateComment on the existing progress comment instead of always calling addComment
• Fallback safety — If updateComment fails (e.g. comment deleted), falls back to addComment so the PR URL is never lost
• Backward compatible — progressCommentId is optional; without it, existing addComment behavior is preserved

Changes

• src/types/index.ts — Added progressCommentId?: string to AgentResult
• src/backends/progressMonitor.ts — Added getProgressCommentId(): string | null public getter
• src/backends/adapter.ts — Captures monitor?.getProgressCommentId() in the returned AgentResult
• src/triggers/shared/agent-execution.ts — Passes agentResult.progressCommentId to lifecycle.handleSuccess
• src/pm/lifecycle.ts — handleSuccess accepts progressCommentId?, uses updateComment+fallback when provided
• tests/unit/pm/lifecycle.test.ts — Added updateComment mock; new tests for update, fallback, and no-progressCommentId cases
• tests/unit/triggers/agent-execution.test.ts — Updated test + new test verifying progressCommentId flows to handleSuccess
• tests/unit/backends/progress.test.ts — New getProgressCommentId() getter tests

Test plan

• handleSuccess updates comment when progressCommentId provided
• handleSuccess falls back to addComment when updateComment fails
• handleSuccess uses addComment when no progressCommentId (backward compat)
• getProgressCommentId() returns null initially, correct ID after posting
• progressCommentId flows through pipeline from AgentResult to handleSuccess
• All 2194 tests passing
• Lint and typecheck passing

Card: https://trello.com/c/ogyS6225/45-the-pr-created-pm-comment-in-implementation-should-replace-last-pm-progress-comment-if-any-rather-than-always-creating-an-additi

🤖 Generated with Claude Code

[nhopeatall]

🔍 Reviewing PR...

[nhopeatall]

LGTM — Clean implementation that threads progressCommentId through the pipeline to replace progress comments with the final "PR created" message.

Verified:

• Data flow is correct: ProgressMonitor.getProgressCommentId() → adapter.ts → agent-execution.ts → lifecycle.handleSuccess()
• Backward compatible: all new parameters are optional, existing behavior preserved when progressCommentId is absent
• Fallback safety: safeUpdateOrAddComment catches updateComment failures and falls back to addComment
• No race condition: getProgressCommentId() is read after backend.execute() completes (minutes later), well after the initial comment promise resolves
• All 86 affected tests pass, typecheck clean, CI green
• updateComment already exists on the PMProvider interface — no new contract needed