Dashboard PR attention links should deep-link to comments and conflicts

[whoisasx]

Problem

On the dashboard/session PR attention states, changes requested and merge conflict actions currently only expose the generic PR link. In some cases the stored PR URL can also be issue-shaped (/issues/{number}), which sends users to a page that is not the actionable PR surface.

This makes it hard to jump directly to the work needed from the dashboard:

• requested changes should take the user to review comments / files
• merge conflicts should take the user to the GitHub conflict resolution page
• generic PR links should normalize GitHub issue-shaped PR URLs to /pull/{number}

Reproduction

1. Create or observe a session with an open GitHub PR.
2. Put the PR into a requested-changes / unresolved-review-comment state.
3. Put the PR into a merge-conflict state.
4. Open the dashboard/session inspector.
5. Check the attention links rendered for requested changes and merge conflict.

Expected

• PR open link points to https://github.com/<owner>/<repo>/pull/<number>.
• Requested changes fallback points to https://github.com/<owner>/<repo>/pull/<number>/files when no direct discussion URL is available.
• Merge conflict action points to https://github.com/<owner>/<repo>/pull/<number>/conflicts.
• Board cards allow those attention links to be clicked directly.

Notes

A real smoke case was verified with whoisasx/test-reverb PR #49: the correct rendered links were /pull/49/conflicts and the direct review discussion anchor.