docs(backup): correct malformed config recovery guidance (#159259)

Replace the retired partial-state archive advice with a verified config-only export. Explain that workspace exclusion preserves ownership discovery and that config-only exports omit include dependencies. Direct users to take a full backup after repairing the config.

The ownership-discovery change in 4d48e9c1e0 intentionally retired partial state archives. Validated against current source, CLI help, retained CLI evidence, independent docs sanity review, and git diff --check. No runtime or test changes.

Co-authored-by: Peter Steinberger <steipete@gmail.com>

docs/install/backups.md

@@ -69,10 +69,18 @@ workspaces remain ordinary workspace files. [Backup CLI](/cli/backup)
 documents every flag, owner-declared regenerable resources, volatile files,
 and verification details.
 
-If the configuration is malformed, `--no-include-workspace` can still produce a
-partial recovery archive for state, config, and credentials. Its skipped
-diagnostics identify agent and plugin ownership that could not be resolved;
-repair the configuration before relying on an archive as complete.
+If the configuration is malformed, state archive creation fails because agent
+and plugin ownership cannot be resolved. `--no-include-workspace` only excludes
+workspace files; it does not bypass ownership discovery. Before repairing the
+configuration, save the active config file:
+
+```bash
+openclaw backup create --only-config --output ~/Backups/openclaw --verify
+```
+
+This saves only the active JSON config file, without parsing it or including
+its `$include` dependencies. Repair the configuration, then rerun the full
+archive command above to protect state, credentials, agents, and workspaces.
 
 Archives are full copies: each run re-uploads everything. They are the right
 tool before an update, reset, uninstall, or machine move, and a reasonable