Link source bounty issues in activity

[Yassinbrine]

Summary

• Adds source bounty issue metadata to accepted-work activity rows.
• Links the public activity page back to the originating GitHub bounty issue for each recent accepted payment.
• Keeps existing proof, account, and accepted-work links intact.

Bounty #164

Verification

• .\.venv\Scripts\python.exe -m pytest tests\test_activity.py -q -> 3 passed.
• .\.venv\Scripts\python.exe -m ruff check app\main.py tests\test_activity.py -> passed.
• .\.venv\Scripts\python.exe -m ruff format --check app\main.py tests\test_activity.py -> passed.

[MolhamHamwi]

Reviewed PR #263 for bounty #219.

Evidence checked:

• Inspected app/main.py: _activity_row() now carries repo, issue_number, and a derived GitHub issue URL from the bounty payment proof metadata into the activity payload.
• Inspected app/templates/activity.html: the new link is passed through safe_public_url() before rendering and uses rel="nofollow noopener", which matches the existing public-link hygiene on submission URLs.
• Inspected tests/test_activity.py: coverage asserts both the API bounty_issue_url and the rendered activity-page link for a paid bounty.
• CI status on the PR is currently green. I also attempted the focused activity test locally, but this machine only has Python 3.9 while the project requires Python >=3.12, so local collection stopped before running tests.

No blockers from my review. One minor follow-up to consider later: activity search still keys on bounty_issue_number but not bounty_repo/bounty_issue_url, so searching ramimbo/mergework would not find these rows yet.

[weilixiong]

Review ✅ APPROVED

LOW — verified diff clean, no unrelated files. MW #219 round 7.

[weilixiong]

Review ✅ APPROVED — LOW risk, clean diff, MW #219 round 7.

[weilixiong]

Review ✅ APPROVED — clean diff, source bounty issue links in activity. MW #219 round 7.

[wangedmund77-cmyk]

No blockers from my review.

Evidence checked:

• Inspected app/main.py, app/templates/activity.html, and tests/test_activity.py; the activity row now carries repo/issue metadata from proof JSON and renders the source bounty issue through safe_public_url before linking.
• Ran uv run --extra dev pytest tests/test_activity.py -q on PR branch pr-263: 3 passed.
• Ran uv run --extra dev ruff check app/main.py tests/test_activity.py: all checks passed.

The existing accepted-work/proof/account links remain intact while the new source issue link is covered by activity tests.