feat(app): add plugin add/remove controls to status popover

[LucasSantana-Dev]

Issue for this PR

Closes #18422

Type of change

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

What does this PR do?

Adds a lightweight plugin management flow to the existing Status popover Plugins tab:

• input to add plugin package/file URL
• + action to append plugin to config.plugin
• x action to remove plugin from the current list

It uses existing config.update + config.get flows and keeps the existing visual structure (no redesign).

How did you verify your code works?

• Ran app package typecheck locally:
  • bun run --cwd packages/app typecheck
• Ran browser-level verification with Playwright against local dev server:
  • Confirmed home screen has no status button (expected)
  • Confirmed session screen shows Status popover
  • Opened Plugins tab and validated add/remove path via new input

Screenshots / recordings

Before add:

After add:

GIF demo:

Checklist

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