[FEATURE]: Allow plugins to add inline home footer status

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

TUI plugins can contribute to home.footer, but additive claims render as full-row siblings above or below the built-in footer. A plugin that needs a compact status indicator on the same row as the version must replace and duplicate the entire built-in footer, losing MCP and plugin health indicators.

Expose a nested home.footer.status slot inside the built-in horizontal footer row, after health indicators and before the flexible spacer and version. This would preserve all existing footer content while allowing plugins to add compact inline status components.