docs(02-01): complete analytics service plan

- Created 02-01-SUMMARY.md with full execution documentation
- Updated ROADMAP.md with phase 2 plan progress (2 of 4 plans with summaries)
- Marked requirements ANLY-01 and ANLY-03 complete in REQUIREMENTS.md
- Added 02-01 key decisions to STATE.md

.planning/STATE.md

@@ -59,6 +59,7 @@ Recent decisions affecting current work:
 - 02-02: Firebase Auth probe: verifyIdToken always throws; 'INVALID'/'Decoding'/'argument' in message = SDK alive = healthy
 - 02-02: Promise.allSettled for probe orchestration — all 4 probes run even if one throws outside its own try/catch
 - 02-02: Per-probe HealthCheckModel.create failure swallowed with logger.error — probe results still returned to caller
+- [Phase 02-backend-services]: 02-01: recordProcessingEvent return type is void (not Promise<void>) — type system prevents accidental await on critical path
 
 ### Pending Todos