docs(telegram): invert chat-gate strategy in docs; tune logs; i18n text

- Bake the final default-allow + mute-the-ineligible strategy into
  docs/ARCHITECTURE.md, docs/FUNCTIONAL.md (+_ru), platform/telegram/README.md,
  the deploy compose comment and the PRERELEASE tracker. The live test proved a
  per-user grant cannot exceed a deny-by-default group (Telegram intersects the
  chat default with the per-user permission), so the chat allows sending by
  default and the bot restricts the ineligible instead of granting the eligible.
- Lower the per-event chat_member trace and eligibility evaluation to Debug;
  keep the actual mute/unmute actions, the startup self-check and warnings at
  Info, so prod logs only what the bot did.
- Update game.searchingForOpponent (Searching -> Waiting for opponent / Поиск ->
  Ждём соперника) and the quickmatch e2e assertions to match.

platform/telegram/internal/bot/bot.go

@@ -270,7 +270,7 @@ func (t *Bot) handleChatMember(ctx context.Context, cm *models.ChatMemberUpdated
 	// Telegram delivers joins, for which chat, the transition, who performed it, and the
 	// new member's send/membership state.
 	canSend, isMember := restrictedSendState(cm.NewChatMember)
-	t.log.Info("chat_member update",
+	t.log.Debug("chat_member update",
 		zap.Int64("chat_id", cm.Chat.ID),
 		zap.Int64("configured_chat_id", t.chatID),
 		zap.Int64("user_id", uid),
@@ -318,7 +318,7 @@ func (t *Bot) handleChatMember(ctx context.Context, cm *models.ChatMemberUpdated
 		t.log.Warn("chat access eligibility failed", zap.Int64("user_id", user.ID), zap.Error(err))
 		return
 	}
-	t.log.Info("chat access evaluated",
+	t.log.Debug("chat access evaluated",
 		zap.Int64("user_id", user.ID), zap.Bool("eligible", eligible), zap.Bool("can_send", currentlyCanSend))
 	// Desired: an eligible user may send, an ineligible one may not. Act only when the
 	// current state differs — idempotent, a no-op for the common eligible member, and it
@@ -356,7 +356,7 @@ func (t *Bot) ApplyChatGate(ctx context.Context, userID int64, allow bool) (bool
 		t.log.Info("chat gate applied", zap.Int64("user_id", userID), zap.Bool("allow", allow))
 		return true, nil
 	default:
-		t.log.Info("chat gate: user not in chat, skipped", zap.Int64("user_id", userID), zap.String("status", string(member.Type)))
+		t.log.Debug("chat gate: user not in chat, skipped", zap.Int64("user_id", userID), zap.String("status", string(member.Type)))
 		return false, nil // absent, or an admin/owner who cannot be restricted
 	}
 }