fix(engine): emit SystemMemory cgroup notice to stderr, not stdout (#2520)

packages/engine/src/services/systemMemory.ts

@@ -93,7 +93,10 @@ function getCgroupLimitMb(): number | null {
 
   _cachedCgroupLimitMb = parseCgroupLimitMb(v2Content, v1Content);
   if (_cachedCgroupLimitMb !== null) {
-    console.info(
+    // stderr, not stdout: this is a diagnostic notice, and commands like `check --json`
+    // write their machine-readable payload to stdout. A banner on stdout corrupts that
+    // payload for any JSON consumer (it broke the Video Agent's hyperframes check parse).
+    console.warn(
       `[SystemMemory] cgroup memory limit detected: ${_cachedCgroupLimitMb} MiB — ` +
         `it governs memory-adaptive render behaviour instead of host RAM.`,
     );