- Add UserService, DMService, InviteService, BlockService
- Migrate REST handlers (channel, DM, invite, block) to use services
- Remove block_handler.go (merged into dm_handler.go)
- Update all services to accept store.Store instead of *db.DB
- Router creates SQLiteStore and passes to service.New()
Handlers are now thin HTTP adapters: parse request → call service →
map error → write JSON. All business logic lives in the service layer.
https://claude.ai/code/session_01CBFF3r84ywkJRWwuqw8zD8