Issue edit and 404 handling implemented.

modified: .agent/rules/issue_management.md ...

modified:   tools/scripts/sync_issues.mjs

docs: add missing journals and update sync script ...

- Added journals 0011 and 0012.
- Updated sync_issues.mjs for robust issue tracking.
- (Deleted closed issue files per cleanup rule).

Docs/Chore: Implement manual issue closure reminder and update development guide rules

Feat: implement two-way issue sync tool with GitBucket