feat: complete UI/UX overhaul - dashboard unification, calendar UX, mobile optimization

- Dashboard redesign as command center with filters, quick actions, inline approve/reject
- Reusable components: BookingRow, BookingFilters, ActionMenu, BookingPreviewModal, BookingEditModal
- Calendar: drag & drop reschedule, eventClick preview modal, grid/list toggle
- Mobile: segmented control bookings/calendar toggle, compact pills, responsive layout
- Collapsible filters with active count badge
- Smart menu positioning with Teleport
- Calendar/list bidirectional data sync
- Navigation: unified History page, removed AdminPending
- Google Calendar OAuth integration
- Dark mode contrast improvements, breadcrumb navigation
- useLocalStorage composable for state persistence

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/composables/useLocalStorage.ts

@@ -0,0 +1,21 @@
+import { ref, watch, type Ref } from 'vue'
+
+export function useLocalStorage<T>(key: string, defaultValue: T): Ref<T> {
+  let initial = defaultValue
+  try {
+    const stored = localStorage.getItem(key)
+    if (stored !== null) {
+      initial = JSON.parse(stored)
+    }
+  } catch {
+    // Invalid JSON in storage, use default
+  }
+
+  const value = ref<T>(initial) as Ref<T>
+
+  watch(value, (newVal) => {
+    localStorage.setItem(key, JSON.stringify(newVal))
+  }, { deep: true })
+
+  return value
+}

frontend/src/composables/useMediaQuery.ts

@@ -0,0 +1,28 @@
+import { ref, onMounted, onUnmounted } from 'vue'
+
+export function useMediaQuery(query: string) {
+  const matches = ref(false)
+  let mediaQuery: MediaQueryList | null = null
+
+  const update = () => {
+    if (mediaQuery) {
+      matches.value = mediaQuery.matches
+    }
+  }
+
+  onMounted(() => {
+    mediaQuery = window.matchMedia(query)
+    matches.value = mediaQuery.matches
+    mediaQuery.addEventListener('change', update)
+  })
+
+  onUnmounted(() => {
+    mediaQuery?.removeEventListener('change', update)
+  })
+
+  return matches
+}
+
+export function useIsMobile() {
+  return useMediaQuery('(max-width: 768px)')
+}