Adjust ACL behavior for "none" mode and make query cache optional

This commit allows skipping authentication, permission checks, and certain filters (e.g., deletions, expirations) when the ACL mode is set to "none" (open relay mode). It also introduces a configuration option to disable query caching to reduce memory usage. These changes improve operational flexibility for open relay setups and resource-constrained environments.

pkg/mode/mode.go

@@ -0,0 +1,18 @@
+// Package mode provides a global ACL mode indicator that can be read by
+// packages that need to know the current access control mode without creating
+// circular dependencies.
+package mode
+
+import "next.orly.dev/pkg/utils/atomic"
+
+// ACLMode holds the current ACL mode as a string.
+// This is set by the ACL package when configured and can be read by other
+// packages (like database) to adjust their behavior.
+var ACLMode atomic.String
+
+// IsOpen returns true if the ACL mode is "none" (open relay mode).
+// In open mode, security filtering (expiration, deletion, privileged events)
+// should be disabled.
+func IsOpen() bool {
+	return ACLMode.Load() == "none"
+}