refactor(worker): slim worker.md from 564 to 80 lines with fork-worker pattern

- Replace verbose prose with concise RULES block (9 non-negotiable rules)
- Compress all phase content to single-paragraph instructions
- Remove: General Implementation Rules, Pre-Return Checklist, Red Flags table, verbose examples, code block templates
- Merge TEAM_MODE Pre-Edit Gate into Phase 0, Red Flags into Team Mode section
- Preserve all <!-- section:X --> markers and ## Phase N: headings for worker-phase parsing

Task: fn-1-prompt-optimization-official-patterns.1

Author: z23cc