docs: add comprehensive refactoring plan for next session

Created detailed 8-10 hour refactoring plan with:
- Session-by-session breakdown (4 sessions)
- Critical, important, and nice-to-have tasks
- Exact commands to run for each step
- Safety protocols and progress tracking
- References to existing audit documents

Plan addresses the 45K lines of code systematically:
- Fix Organization type conflicts (50+ files)
- Split large service files (1,145 lines → 5 files)
- Consolidate documentation (15+ files → organized structure)
- Add missing unit tests (target 98% coverage)
- Enable TypeScript strict mode
- Optional: Performance optimizations and cleanup

Each session has clear goals, time estimates, and success criteria.

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Co-Authored-By: Claude <noreply@anthropic.com>

Author: ScientiaCapital