refactor(oauth): replace legacy oauth cache with standard ram cache and add pubsub synchronization

- Replaced custom map-based cache in apps/oauth/cache.go with standard pkg/cache/ram framework.
- Implemented Redis Pub/Sub invalidation channels for distributed token and user cache synchronization.
- Created apps/oauth/cache_test.go to verify local cache operations and pub/sub broadcasts.

refactor(cache): generic RAM cache with CoW and unified preheating

Replaced L2 Redis cache and old cache package with process-local generic pkg/cache/ram. Implemented Copy-on-Write for reads, fine-grained locks per type for writes, and unified preheating in bootstrap. Changed cache invalidation to lazy-loading to resolve SQLite deadlocks during transactions.

internal/apps/edge/nodeip/nodeip.go

@@ -104,3 +104,11 @@ func DetectLocal() string {
 	}
 	return bestIP
 }
+
+// ResetCacheForTest clears the cached IP.
+func ResetCacheForTest() {
+	cacheMu.Lock()
+	cachedIP = ""
+	lastDetected = time.Time{}
+	cacheMu.Unlock()
+}