feat: implement Redis caching for analytics endpoints with fallback to database

app/core/middleware/__init__.py

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+"""Application middleware components."""

app/core/middleware/cache_monitor.py

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+"""Middleware that logs cache availability transitions."""
+from __future__ import annotations
+
+import logging
+from starlette.types import ASGIApp, Receive, Scope, Send
+
+from app.core.cache import cache_manager
+from app.core.config import settings
+
+logger = logging.getLogger(__name__)
+
+
+class CacheAvailabilityMiddleware:
+    """Logs when Redis cache becomes unavailable or recovers."""
+
+    def __init__(self, app: ASGIApp) -> None:
+        self.app = app
+        self._last_state: bool | None = None
+
+    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
+        if scope["type"] == "http" and settings.redis_enabled:
+            self._log_transition()
+        await self.app(scope, receive, send)
+
+    def _log_transition(self) -> None:
+        available = cache_manager.is_available
+        if self._last_state is None:
+            self._last_state = available
+            if not available:
+                logger.warning("Redis cache unavailable, serving responses without cache")
+            return
+        if available == self._last_state:
+            return
+        if available:
+            logger.info("Redis cache connectivity restored; caching re-enabled")
+        else:
+            logger.warning("Redis cache unavailable, serving responses without cache")
+        self._last_state = available