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.

gateway/internal/push/hub_test.go

@@ -54,3 +54,21 @@ func TestHubUnsubscribeClosesChannel(t *testing.T) {
 	}
 	h.Publish(push.Event{UserID: "u"}) // must not panic
 }
+
+func TestHubHasSubscribers(t *testing.T) {
+	h := push.NewHub(2)
+	if h.HasSubscribers("u") {
+		t.Fatal("no subscribers yet")
+	}
+	_, cancel := h.Subscribe("u")
+	if !h.HasSubscribers("u") {
+		t.Error("u should be reported online after Subscribe")
+	}
+	if h.HasSubscribers("other") {
+		t.Error("other has no subscription")
+	}
+	cancel()
+	if h.HasSubscribers("u") {
+		t.Error("u should be offline after unsubscribe")
+	}
+}