Add TDD implementation plan and todo tracker
19-step incremental build plan for the meetup-cfp platform, broken into small TDD prompts (RED/GREEN/REFACTOR) designed for execute-plan. Covers project scaffolding through Docker deployment, with test factories, permission integration tests, and business logic validation at each step.
- plan.md - Detailed step-by-step implementation plan with code-gen prompts for each phase
- todo.md - Checkbox tracker mirroring the plan (103 sub-steps)