Keep active thread state consistent after browser resume

[ymichael]

Summary

• Add an active-thread lifecycle cache owner that invalidates the active thread bundle after real browser suspend/resume signals.
• Wire pagehide/hidden visibility to mark suspend and cancel active fetches; wire pageshow, visible visibilitychange, and focus to one deduped active-thread catch-up.
• Extend websocket reconnect catch-up to include thread conversation outline and thread detail bootstrap, matching the active thread bundle.

Active Thread Bundle

The browser-resume path refreshes the currently observed thread IDs across:

• thread detail
• thread detail bootstrap
• thread default execution options
• queued messages
• prompt history
• pending interactions
• timeline
• conversation outline

This is intentionally scoped to active thread state. It does not duplicate PR #440's broader reconnect audit or its terminal/automation reconnect additions.

Root Cause

Before this PR, mobile sleep/resume depended on per-query React Query focus behavior unless the websocket produced a clean reconnect/open callback. Timeline could recover via focus/pageshow refetch, while queued messages, pending interactions, default options, and bootstrap-like neighboring state could remain stale because some of those queries explicitly opt out of focus refetch or use long/infinite stale times. Reconnect catch-up also covered timeline but missed conversation outline and bootstrap.

Before / After

Before: if the phone locked on a bad network and websocket events were missed without a clean reconnect notification, active thread surfaces could drift: timeline could show accepted/new rows while queue/pending/composer-adjacent state still reflected the pre-sleep snapshot.

After: browser resume invalidates the active thread bundle as one unit, independent of individual query focus settings. Websocket reconnect catch-up also covers timeline outline and bootstrap alongside the existing thread/queue/pending/prompt/default-option invalidations.

Verification

• pnpm exec turbo run test --filter=@bb/app -- query-client.test.ts system-cache-effects.test.ts cache-owner-registry.test.ts
• pnpm exec turbo run typecheck --filter=@bb/app