Disable automatic Git maintenance

[tianrking]

Summary

• disable maintenance.auto as well as the legacy gc.auto on the primary checkout
• apply the same pair of settings to every checked-out submodule
• cover both configuration writes with a command-manager regression test
• regenerate the committed action bundle

Git 2.54's default background maintenance is no longer governed by gc.auto. Disabling both settings prevents an asynchronous maintenance run from mutating shallow metadata while checkout is deepening history.

Fixes #2437

Validation

• npm run format-check
• npm test (129 passed)
• npm run build
• git diff --check

npm run lint is currently blocked in this Windows checkout by repository-wide pre-existing CRLF and TypeScript .js-import resolver findings, including files outside this change.