fix: commit remaining durable changes — procmgr SIGCHLD + ps2d async

- procmgr.rs: SIGCHLD EPERM → debug (backed by P0-procmgr-sigchld-debug.patch)
- 40_ps2d.service: type notify → oneshot_async (PS/2 doesn't block boot)

Both were working-tree changes flagged by Oracle as not committed.

recipes/core/base/init.initfs.d/40_ps2d.service

@@ -5,4 +5,6 @@ condition_architecture = ["x86", "x86_64"]
 
 [service]
 cmd = "ps2d"
-type = "notify"
+# oneshot_async: do not block boot waiting for PS/2. On modern hardware
+# without a real PS/2 controller, the driver may take time to probe.
+type = "oneshot_async"