docs: sync documentation with latest codebase state

- Update Activity Log with 108 missing commits (48 backend + 60 frontend)
- Update version references: backend v2.8.79, frontend v2.8.94
- Update migration count: 18 migrations (0000-0017)
- Update Telegram Mini App Flow to v2.8.94
- Update Payment Flow - Scanner to 2026-06-05
- Update all architectural and database references

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

mongo-to-pg-migration-prd.md

@@ -1,6 +1,6 @@
 ## Status Update — 2026-06-03
 
-**Backend version:** v2.8.56
+**Backend version:** v2.8.79
 **Updated:** 2026-06-03
 
 ### Infrastructure Milestones Reached
@@ -35,7 +35,7 @@ The migration has reached **write-parity**: every entity is dual-written to Post
 
 **Status:** In Progress — Foundation tasks complete, dual-write coverage 100%
 **Date:** 2026-06-02 (audit) / updated 2026-06-02 (9 tasks completed)
-**Backend version:** 2.8.44 on `integrate-main-into-development`
+**Backend version:** 2.8.79 on `integrate-main-into-development`
 **Source:** Automated audit via `mongo-to-pg-migration-audit` workflow (49 agents, 528 DB operations catalogued)
 **Target:** Full migration — 23 Mongoose models → Postgres + Drizzle ORM