feat: unified station mode with POS + repairs desk view

Phase 1: Station shell
- /station route replaces /pos (with redirect)
- Shared lock screen, activity tracking, auto-lock timer
- Permission-gated tab bar (POS | Repairs | Lessons)
- POSRegister embedded mode (skip lock/timer/topbar)
- Sidebar navigates to /station

Phase 2: Repairs station — front desk
- Status bar with count badges per status group, clickable filters
- Ticket queue panel with search and status filtering
- Ticket detail panel with status progress, notes, photos, line items
- Full stepped intake form: customer → item → problem/estimate → review
- Service template quick-add for line items

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/admin/src/stores/station.store.ts

@@ -0,0 +1,13 @@
+import { create } from 'zustand'
+
+type StationTab = 'pos' | 'repairs' | 'lessons'
+
+interface StationState {
+  activeTab: StationTab
+  setActiveTab: (tab: StationTab) => void
+}
+
+export const useStationStore = create<StationState>((set) => ({
+  activeTab: 'pos',
+  setActiveTab: (tab) => set({ activeTab: tab }),
+}))