fix: address security review findings, implement real cache clearing, and fix lifecycle promises

shared/modules/dashboard/dashboard.types.ts

@@ -59,6 +59,12 @@ export const ClientStatsSchema = z.object({
 
 export type ClientStats = z.infer<typeof ClientStatsSchema>;
 
+// Action Schemas
+export const MaintenanceModeSchema = z.object({
+    enabled: z.boolean(),
+    reason: z.string().optional(),
+});
+
 // WebSocket Message Schemas
 export const WsMessageSchema = z.discriminatedUnion("type", [
     z.object({ type: z.literal("PING") }),