feat(pm): replace PR comment links with native attachments/remote links

[aaight]

Summary

• Replace comment-based PR links with native attachments/remote links — Trello cards now get URL attachments (sidebar links) and JIRA issues get remote links (Links section with GitHub icon) when a PR is created
• Comment as fallback only — PR created: <url> comment is posted only if linkPR fails
• New linkPR abstraction added to PMProvider interface so each provider uses its optimal API
• JIRA addRemoteLink — Leverages jira.js v5's issueRemoteLinks.createOrUpdateRemoteIssueLink() with PR URL as globalId for idempotency
• Full test coverage — lifecycle tests, adapter tests, and JIRA client tests

Card: https://trello.com/c/ZceuaSMm/84-lets-research-and-plan-how-we-can-cleanly-attach-pr-links-probably-as-attachments-to-trello-cards-jira-issues-when-creating-a-pr

Test plan

• All unit tests passing (2706 tests)
• TypeScript type checking passes
• Linting passes
• linkPR called on implementation success with prUrl
• linkPR not called when no prUrl or for non-implementation agents
• linkPR success → no comment posted
• linkPR failure → comment fallback fires (with and without progressCommentId)
• JIRA addRemoteLink calls jira.js with correct params (globalId = PR URL, relationship = "Pull Request", GitHub favicon icon)
• Trello linkPR delegates to trelloClient.addAttachment
• JIRA linkPR delegates to jiraClient.addRemoteLink

🤖 Generated with Claude Code

[nhopeatall]

🔍 Reviewing PR...

[nhopeatall]

LGTM — Clean abstraction that replaces comment-based PR links with native provider attachments/remote links, with a well-designed comment fallback.

The implementation is correct:

• linkPR added to PMProvider interface with both adapters implementing it appropriately (JIRA → remote links, Trello → URL attachments)
• JIRA leverages createOrUpdateRemoteIssueLink with globalId = prUrl for idempotency — nice touch
• Fallback logic correctly handles: linkPR failure → comment with/without progressCommentId → addComment as last resort
• extractPRTitle is simple and handles edge cases (trailing paths, non-GitHub URLs)
• Test coverage is thorough across all paths including cascading failures