Stage 9: Telegram integration (connector side-service, Mini App, out-of-app push)

New platform/telegram connector (own container, bot token only there):
- go-telegram/bot long-poll loop: /start deep-links + Mini App launch button.
- gRPC API pkg/proto/telegram/v1 (Telegram service): ValidateInitData, Notify
  (renders a localized message + deep-link button), SendToUser/SendToGameChannel
  (admin, wired in Stage 10). Generic methods are platform-agnostic (external_id).
- Bot API base override for Telegram's test environment; Dockerfile + compose
  (VPN sidecar, no public ingress); README.

Gateway:
- initData validation relocated from the gateway into the connector; the gateway
  calls ValidateInitData over gRPC (GATEWAY_CONNECTOR_ADDR), drops the bot token,
  and deletes internal/auth.
- Out-of-app push: runPushPump routes events whose recipient has no live in-app
  stream to connector.Notify, gated by /internal/push-target + the in-app-only
  flag (race-free de-dup); HasSubscribers added to the push hub.

Backend:
- Migration 00007 accounts.notifications_in_app_only (default true) + jetgen.
- ProvisionTelegram seeds a new account's language/display name from the launch
  fields; IdentityExternalID reverse lookup; /internal/push-target handler.

UI:
- Telegram Mini App launch: detect initData, apply themeParams, authTelegram,
  route the deep-link start_param (g/i/f); /telegram/ guard redirects outside
  Telegram. Vite relative base + telegram-web-app.js. In-app-only profile toggle;
  share-to-Telegram link for a friend code. Vitest + Playwright coverage.

Wire/docs/CI: fbs Profile/UpdateProfileRequest gain notifications_in_app_only
(Go + TS); go.work uses ./platform/telegram; go-unit.yaml covers it; PLAN,
ARCHITECTURE, FUNCTIONAL (+ru), UI_DESIGN, READMEs updated.

CLAUDE.md

@@ -111,7 +111,8 @@ backend/                     # module scrabble/backend
   internal/server/           # gin engine, /api/v1 groups, X-User-ID, probes
   internal/inttest/          # //go:build integration Postgres-backed tests
 docs/  .gitea/workflows/  PLAN.md  CLAUDE.md  README.md
-gateway/  ui/  pkg/  platform/   # added by their stages
+gateway/  ui/  pkg/              # added by their stages
+platform/telegram/               # Telegram connector side-service (Stage 9): bot + gRPC API
 ```
 
 ## Build & test
@@ -121,6 +122,7 @@ go build ./backend/...          # per module ('./...' from the root won't span t
 go vet ./backend/...
 gofmt -l .                      # must print nothing
 go test -count=1 ./backend/...
+go build ./platform/telegram/... && go test ./platform/telegram/...  # Telegram connector (Stage 9)
 go run ./backend/cmd/backend    # /healthz, /readyz on :8080
 
 cd ui && pnpm install && pnpm check && pnpm test:unit && pnpm build  # the UI (Stage 7+)