feat(server): 资源监控——/proc 与 cgroup 采样、/system/resources 趋势，心跳带进程 CPU

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Cxwgnn2pbzQ7rXv3rq7fei

apps/server/vitest.config.ts

@@ -22,6 +22,7 @@ const UNIT = [
   "test/modules.test.ts",
   "test/sse.test.ts",
   "test/static.test.ts",
+  "test/system-resources.test.ts",
 ];
 
 const SERIAL = [