feat(followup): implement PLAN-FOLLOWUP.md gap fixes

Complete implementation of 7 slices addressing E2E testing gaps:

Slice 0+1: Wire Actions + ReasonPrompt
- FocusView now uses useActions hook instead of direct act() calls
- Added pendingAction state pattern for skip/defer/complete actions
- ReasonPrompt integration with proper confirm/cancel flow
- Tags support in DecisionEntry interface

Slice 2: Drag Reorder UI
- Installed @dnd-kit (core, sortable, utilities)
- QueueView with DndContext, SortableContext, verticalListSortingStrategy
- SortableQueueItem wrapper component using useSortable hook
- pendingReorder state with ReasonPrompt for reorder reasons
- Cmd+Up/Down keyboard shortcuts for accessibility
- Fixed: Store item ID in PendingReorder to avoid stale queue reference

Slice 3: System Tray Integration
- tray.rs with TrayState, setup_tray, toggle_window_visibility
- Menu with Show/Quit items
- Left-click toggles window visibility
- update_tray_badge command updates tooltip with item count
- Frontend wiring in AppShell

Slice 4: E2E Test Updates
- Fixed test selectors for InboxView, Queue badge
- Exposed inbox store for test seeding

Slice 5: Staleness Visualization
- Already implemented in computeStaleness() with tests

Slice 6: Quick Wiring
- onStartBatch callback wired to QueueView
- SyncStatus rendered in nav area
- SettingsView renders Settings component

Slice 7: State Persistence
- settings-store with hydrate/update methods
- Tauri backend integration via read_settings/write_settings
- AppShell hydrates settings on mount

Bug fixes from code review:
- close_bead now has error isolation (try/catch) so decision logging
  and queue advancement continue even if bead close fails
- PendingReorder stores item ID to avoid stale queue reference

E2E tests for all ACs (tests/e2e/followup-acs.spec.ts):
- AC-F1: Drag reorder (4 tests)
- AC-F2: ReasonPrompt integration (7 tests)
- AC-F5: Staleness visualization (3 tests)
- AC-F6: Batch mode (2 tests)
- AC-F7: SyncStatus (2 tests)
- ReasonPrompt behavior (3 tests)

Tests: 388 frontend + 119 Rust + 32 E2E all passing

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package-lock.json

@@ -8,6 +8,9 @@
       "name": "mission-control",
       "version": "0.1.0",
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+        "@dnd-kit/sortable": "^10.0.0",
+        "@dnd-kit/utilities": "^3.2.2",
         "@tanstack/react-query": "^5.75.0",
         "@tauri-apps/api": "^2.3.0",
         "@tauri-apps/plugin-shell": "^2.2.0",
@@ -573,6 +576,59 @@
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       }
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