fix: prioritize pull comment URLs over action runs

[pilipilisbot]

Summary

• prefer pull/issue/comment URLs over workflow run links when parsing GitHub notification bodies
• strip trailing punctuation from extracted GitHub URLs
• keep the selected primary URL first in the context URL list

Tests

• .venv/bin/pytest tests/test_parser.py tests/test_queue.py
• git diff --check

[pilipilisbot]

Post-merge cleanup complete for #49.

• Confirmed the PR merged as 705fe306eb44b08de43a591fc5bc9207773a60f0.
• Verified post-merge main workflows passed: tests https://github.com/pilipilisbot/github-agent-bridge/actions/runs/26409199908 and release https://github.com/pilipilisbot/github-agent-bridge/actions/runs/26409199955.
• Fetched/pruned origin; GitHub had deleted origin/fix-url-priority.
• Moved the canonical checkout back to clean main at v0.18.7 (31c8a48907fcb8f2f3dae41a2c3414cb7e88382c) and deleted the stale local fix-url-priority branch.
• No dedicated PR worktree existed, so there was no separate worktree to remove.