docs: update local-first migration plan and CLAUDE.md to reflect 19/19 completion

- Migration plan Phase 3: updated from 8/8 to 19/19 with full app table
- Added server-side logic column showing what remains per app
- Listed 3 apps not migrated (ManaCore, Matrix, Playground) with reasons
- CLAUDE.md: clarified 19/22 count and added "not migrated" note

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -522,7 +522,7 @@ Logged in:  App → IndexedDB → UI → SyncEngine → mana-sync (Go) → Postg
                                   ← WebSocket push ←
 ```
 
-### Migrated Apps
+### Migrated Apps (19/22)
 
 | App | Collections | Status |
 |-----|------------|--------|
@@ -546,6 +546,8 @@ Logged in:  App → IndexedDB → UI → SyncEngine → mana-sync (Go) → Postg
 | SkilltTree | skills, activities, achievements | Done |
 | CityCorners | locations, favorites | Done |
 
+**Not migrated (no CRUD data model):** ManaCore (hub), Matrix (protocol client), Playground (stateless)
+
 ### Dev Commands (Local-First Stack)
 
 ```bash