feat(ui): menu-bar live monitor (post-0.5)

[sepehr-safari]

Scope (post-0.5, deferred)

A macOS menu-bar live monitor: a status_item showing live-capture state
with a badge (active sessions / critical-failure count) and quick actions
(start/stop, show window). Deferred out of the 0.5.0 launch to keep the first
release focused on packaging + docs; scheduled as a fast follow (0.5.1).

Notes / feasibility

• The platform tray service (services.createTray / updateTrayTitle /
  updateTrayMenu, TrayOptions) is reachable the same way live notifications
  are (ADR-0011): the effects-bound PlatformServices on the loop thread
  (fx.services). Confirm the seam + any tray permission as the first step.
• Ties into the live-capture model (feat(ui): live capture view — streaming timeline #59) and notifications (feat(capture): OS notifications on critical failures #60): the badge
  reflects model.live status and the critical-failure count.

Acceptance criteria (when scheduled)

• A status-item appears with a live badge that updates as capture streams; quick
  actions dispatch the same Msgs as the in-window controls.
• native build + native test green; permission declared in app.zon.

Not part of the 0.5.0 milestone.