Add safe configuration commands

docs/roadmap.md

@@ -67,6 +67,17 @@ For deployment-readiness work that cuts across feature areas, see
   - `[x]` A recursive CLI test fails when a future argument is added without a
     description.
 
+- `[x]` Add a safe configuration workflow.
+  Acceptance criteria:
+  - `[x]` `geth config path/show/validate` identify the selected file, expose
+    built-in defaults when it is absent, and report parse or semantic errors.
+  - `[x]` `geth config set` supports the common Iroh and live-sync settings,
+    preserves unrelated TOML and comments, and validates before replacement.
+  - `[x]` Updates use a same-directory temporary file and clearly report that a
+    daemon restart is required.
+  - `[x]` Tests cover comment preservation, invalid-update rollback, and
+    creation from defaults in an isolated temporary home.
+
 - `[x]` Document task-oriented user stories.
   Acceptance criteria:
   - `[x]` Workflows cover disposable evaluation, persistent background use,