Build LiveNowPanel UI and harden deep-link navigation for cross-scope click-to-focus

[fayekelmith]

Summary

Generated with Hive.

• LiveNowPanel: compact, collapsible canvas overlay answering "what needs me, and what's running?" at a glance — pure presentation over the attention feed + live feature state already tracked by OrgCanvasBackground (no new fetch/poll). Renders nothing at all when there's nothing active (zero chrome). Row clicks dispatch pendingDeeplink commands through the canvas chat store, reusing the same navigation path as chat deeplink chips.
• Harden deep-link navigation: extracted cross-scope navigation into a leaf module deeplinkNavigation.ts. Fixes two cross-scope bugs: (1) silent no-op when drilling into a node on a different sub-canvas (now climbs to root, waits for the canvas swap, then drills in), and (2) stale currentRef closure producing a wrong focus zoom (canvas data now resolved at call time via refs after navigation resolves). The navigation is guarded against mid-flight re-entry, never throws, and always clears the pendingDeeplink slot.

Test plan

• npx vitest run src/__tests__/unit/canvas/liveNowPanel.test.tsx src/__tests__/unit/canvas/nodeDeepLink.test.ts — 23/23 passing
• New unit tests for the Live Now panel (grouping, collapse, overflow, empty-state renders nothing) and hardened deeplink navigation (cross-scope jump, skip-when-on-target, stale-ref scroll fix)