feat: add referral network graph visualization admin API

4 endpoints for referral network analysis: full graph with batched
aggregation queries, user detail with recursive CTE branch counting,
campaign detail with conversion metrics, and search with LIKE escaping.

All endpoints rate-limited, scoped queries to prevent full-table scans,
depth-limited recursive CTE, fail_closed on expensive graph endpoint.

app/cabinet/routes/__init__.py

@@ -20,6 +20,7 @@ from .admin_pinned_messages import router as admin_pinned_messages_router
 from .admin_policies import router as admin_policies_router
 from .admin_promo_offers import router as admin_promo_offers_router
 from .admin_promocodes import promo_groups_router as admin_promo_groups_router, router as admin_promocodes_router
+from .admin_referral_network import router as admin_referral_network_router
 from .admin_remnawave import router as admin_remnawave_router
 from .admin_roles import router as admin_roles_router
 from .admin_sales_stats import router as admin_sales_stats_router
@@ -99,6 +100,7 @@ router.include_router(admin_wheel_router)
 router.include_router(admin_tariffs_router)
 router.include_router(admin_servers_router)
 router.include_router(admin_stats_router)
+router.include_router(admin_referral_network_router)
 router.include_router(admin_sales_stats_router)
 router.include_router(admin_ban_system_router)
 router.include_router(admin_broadcasts_router)

app/utils/cache.py

@@ -400,9 +400,11 @@ return c
             return fail_closed
 
     @staticmethod
-    async def is_rate_limited(user_id: int, action: str, limit: int, window: int) -> bool:
+    async def is_rate_limited(
+        user_id: int, action: str, limit: int, window: int, *, fail_closed: bool = False,
+    ) -> bool:
         key = cache_key('rate_limit', user_id, action)
-        return await RateLimitCache._atomic_rate_check(key, limit, window)
+        return await RateLimitCache._atomic_rate_check(key, limit, window, fail_closed=fail_closed)
 
     @staticmethod
     async def reset_rate_limit(user_id: int, action: str) -> bool: