Update ROADMAP.md with technical debt implementation status

- Added implementation status section (9/24 items complete, 38%)
- Marked completed items with ✅ (Phases 0-3 partial)
- Marked pending items with ⏳ and deferred items
- Added commit references for tracking
- Progress summary: 124 lines eliminated, 1 critical vuln fixed, 54 tests passing

Author: rsousa88