- Add data-testid="roster-dot-{name}" to both active and idle dot spans for testability
- Change idle badge from grey (#888, #555, #333) to green (#3fb950, #3fb95015, #3fb95040)
- Update idle label from "idle" to "available" to reinforce positive availability signal
- Update tooltip from "— idle" to "— available" for consistency
- Active/running agents retain blue (#58a6ff) pulsing dot styling unchanged
- Add 4 new Vitest tests covering green idle dot, green badge styling, blue active dot, and blue active badge
Closes story 81: Agent roster badges show availability state
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>