feat: add local doctor checks

README.md

@@ -100,6 +100,7 @@ The bootstrap implementation provides:
 - `geth daemon service install|uninstall|start|stop|status|print`
 - `geth status`
 - `geth wait daemon|peer|sync --timeout-ms <ms>`
+- `geth doctor`
 - `geth backup create --out <dir>`
 - `geth backup restore <backup-dir> --target-home <dir>`
 - `geth node id`
@@ -434,6 +435,14 @@ the private SSH keys.
 `geth backup restore <backup-dir> --target-home <dir>` restores into a separate
 empty target home for validation. It refuses to overwrite a non-empty target.
 
+## Doctor
+
+`geth doctor` is a local operational check that works even when the daemon is
+not reachable. It checks config parsing, local daemon socket health,
+`ssh-keygen` availability, metadata-store readability, imported peer-card
+validity, and representative peer grants when local metadata is available. Use
+`--json` for scripts.
+
 ## Owner And Node Management
 
 The intended owner setup is SSH-admin-rooted: