feat(progress): post immediate comment on ProgressMonitor.start()

[aaight]

Summary

• Immediate progress comment — Posts a "🚀 Starting" comment to the work item (Trello/JIRA) the moment ProgressMonitor.start() is called, eliminating the 5-minute wait for the first timer tick
• Race condition handled — Stores the initial comment promise and awaits it in tick() so the first tick updates the same comment instead of creating a duplicate
• No-LLM initial message — Static acknowledgment format (formatInitialMessage()) for instant response; saves LLM calls for real progress updates
• Graceful failure — Initial comment errors are caught and logged without crashing; subsequent ticks continue normally
• Tests updated — 4 new test cases + all existing tests updated to reflect the new flow (initial comment at start(), ticks update via updateComment)

Card: https://trello.com/c/ABKnb87g/37-when-implementing-we-should-create-a-new-comment-on-the-card-issue-immediately-that-we-will-continuously-update-as-we-go-right-n

Test plan

• posts initial comment immediately on start() — verifies addComment called at start with correct message
• first tick updates initial comment (not creates new) — verifies race condition resolved correctly
• handles failure of initial comment gracefully — verifies WARN log, no crash
• no crash when PM provider is null on start() — verifies null-safe path
• All existing tick tests updated to match new behavior (initial comment at start(), ticks updateComment)
• 2101 total tests passing, zero type errors, lint warnings are pre-existing

🤖 Generated with Claude Code

[nhopeatall]

🔍 Reviewing PR...

[nhopeatall]

LGTM — Clean implementation of immediate progress comments. The race condition between postInitialComment() and the first tick() is correctly handled by awaiting the stored promise. Error paths degrade gracefully: if the initial comment fails, progressCommentId stays null and the existing fallback in postProgress() creates a new comment on the first tick. Tests cover all the important scenarios.