fix: unify Hackathon_10th directory naming and file name conventions

- Merge `hackathon_10th/` (lowercase) into `Hackathon_10th/` (uppercase)
  to match other hackathon directories
- Rename `[WeeklyReports]` to `[WeeklyReport]` (remove extra 's') per
  the naming convention in issue #2
- Add missing `[WeeklyReport]` prefix for Manfredss's 2nd report
- Fix zty-king's file: normalize separators (`_` → `.`, `-` → `~`)
  and add `.md` suffix

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Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

Author: 3 people