feat: TUI dashboard — worktrees, CI, PRs in one view

[erishforG]

Vision (v1.0: Ticket lifecycle complete)

Real-time terminal dashboard showing all worktrees, CI, and PR status in one view.

Proposal

parsec dashboard    # launch TUI dashboard
parsec dash         # alias

Layout

┌─ Worktrees ──────────────────┬─ CI Status ─────────────┐
│ ● CL-2283 Add rate limiting  │ PR #42: ✓ 7/7 passed    │
│ ● CL-2284 Fix auth bug       │ PR #43: ● 3/7 running   │
│ ○ CL-2291 API endpoints      │ (no PR)                  │
├─ Sprint Board ───────────────┼─ Conflicts ──────────────┤
│ In Progress: 3               │ src/api.rs: CL-2283,     │
│ In Review: 2                 │             CL-2291       │
│ Done: 5                      │                           │
└──────────────────────────────┴──────────────────────────┘

• Real-time CI polling (5s interval)
• Keyboard navigation (j/k, Enter to switch worktree)
• Built with ratatui

Reference

• Sapling: ISL web UI (sl web)
• GitButler: desktop app

Milestone

v1.0