feat(tui): add inline home footer slot - #48798

Issue for this PR

Closes #48797

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Adds a typed home.footer.status slot inside the built-in home footer row. Plugins can now render compact status components alongside the built-in MCP/plugin indicators and version without replacing the whole footer.

The built-in registry is loaded lazily during reconciliation to avoid a module cycle when a built-in plugin mounts a nested slot.

How did you verify your code works?

• Full repository pre-push typecheck: 35/35 tasks passed
• packages/plugin: typecheck passed
• packages/tui: typecheck passed
• Focused home-footer tests: 2 passed
• Full TUI suite: 1,343 passed, 4 skipped; two existing shell-output tests timed out
• Documentation typecheck, generated check, build, and link validation passed
• Lint passed with two pre-existing warnings in packages/tui/src/plugin/context.tsx

The plugin test suite has one environment-specific failure caused by macOS resolving /var as /private/var; the remaining 8 tests pass.

Screenshots / recordings

Before (it was imposible to get the slot on the same row, always above or below, which doesnt look the best)

After

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR