Add dedicated actor detail page accessible from both web and TUI surfaces.
Web:
- /actor/<hex> page with live-updating stats, sparkline charts for message
rate and mailbox depth, status badge, worker assignment
- Actor addresses in overview and actors pages now link to detail page
- Actors page detail panel links to dedicated detail page
TUI:
- ViewMode::ActorDetail with per-actor sparklines (rate + mailbox)
- Enter on actor row opens detail, Esc returns to previous view
- Per-actor ring buffer history (60 samples) tracked in App state
Authored by Claude, lovingly guided by Zachery Aaron Shores-Chmielewski
