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.

backend/internal/account/provision_test.go

@@ -0,0 +1,48 @@
+package account
+
+import (
+	"strings"
+	"testing"
+	"unicode/utf8"
+)
+
+// TestTelegramSeed covers the pure mapping from Telegram launch fields to the
+// create-time account seed: supported-language detection (bare and region-tagged),
+// the first-name / username display-name precedence, and trimming.
+func TestTelegramSeed(t *testing.T) {
+	cases := map[string]struct {
+		languageCode, username, firstName string
+		wantLang, wantName                string
+	}{
+		"ru bare":           {"ru", "user", "Иван", "ru", "Иван"},
+		"en region-tagged":  {"en-US", "user", "John", "en", "John"},
+		"ru region-tagged":  {"ru-RU", "", "Пётр", "ru", "Пётр"},
+		"unknown language":  {"fr", "frodo", "Frodo", "", "Frodo"},
+		"empty language":    {"", "neo", "Neo", "", "Neo"},
+		"first name wins":   {"en", "handle", "Real Name", "en", "Real Name"},
+		"username fallback": {"en", "handle", "", "en", "handle"},
+		"both empty":        {"en", "", "", "en", ""},
+		"trimmed":           {" RU ", "  ", "  Anna  ", "ru", "Anna"},
+	}
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			got := telegramSeed(tc.languageCode, tc.username, tc.firstName)
+			if got.preferredLanguage != tc.wantLang {
+				t.Errorf("preferredLanguage = %q, want %q", got.preferredLanguage, tc.wantLang)
+			}
+			if got.displayName != tc.wantName {
+				t.Errorf("displayName = %q, want %q", got.displayName, tc.wantName)
+			}
+		})
+	}
+}
+
+// TestTelegramSeedTruncatesLongName checks an over-long Telegram name is capped to
+// maxDisplayName runes (counted in runes, not bytes).
+func TestTelegramSeedTruncatesLongName(t *testing.T) {
+	long := strings.Repeat("я", maxDisplayName+5)
+	got := telegramSeed("ru", "", long)
+	if n := utf8.RuneCountInString(got.displayName); n != maxDisplayName {
+		t.Errorf("display name rune count = %d, want %d", n, maxDisplayName)
+	}
+}