feat: Python example bot + mark completed PLAN items

Add minimal Python webhook bot (zero deps, stdlib only).
Mark Docker, rate limiting, example bots, tutorial as done in PLAN.md
— all were already implemented.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

PLAN.md

@@ -416,12 +416,12 @@ Integrated into the fight viewer:
 - [x] API docs page
 
 ### Phase 4: Go Live
-- [ ] Docker containerization
+- [x] Docker containerization
 - [ ] Anonymous VPS deployment
 - [ ] Tor hidden service (optional)
-- [ ] Rate limiting + abuse prevention
-- [ ] Example bot implementations (at least 2)
-- [ ] "How to Build a Fighter" tutorial
+- [x] Rate limiting + abuse prevention
+- [x] Example bot implementations (at least 2)
+- [x] "How to Build a Fighter" tutorial
 
 ### Phase 5: Betting (Future)
 - [ ] Cashu mint integration