refactor: code efficiency improvements (Issues #9-13, #15, #17-20)

Backend:
- Extract shared hard-delete authorization utility (#9)
- Extract Prisma include constants per entity (#11)
- Fix N+1 query pattern in events findAll (#12)
- Extract shared date utility functions (#13)
- Move vehicle utilization filtering to DB query (#15)
- Add ParseBooleanPipe for query params
- Add CurrentDriver decorator + ResolveDriverInterceptor (#20)

Frontend:
- Extract shared form utilities (toDatetimeLocal) and enum labels (#17)
- Replace browser confirm() with styled ConfirmModal (#18)
- Add centralized query-keys.ts constants (#19)
- Clean up unused imports, add useMemo where needed (#19)
- Standardize filter button styling across list pages

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

frontend/src/lib/enum-labels.ts

@@ -0,0 +1,41 @@
+/**
+ * Enum Display Labels
+ * Centralized mapping of enum values to human-readable labels
+ */
+
+export const DEPARTMENT_LABELS: Record<string, string> = {
+  OFFICE_OF_DEVELOPMENT: 'Office of Development',
+  ADMIN: 'Admin',
+  OTHER: 'Other',
+};
+
+export const ARRIVAL_MODE_LABELS: Record<string, string> = {
+  FLIGHT: 'Flight',
+  SELF_DRIVING: 'Self Driving',
+};
+
+export const EVENT_TYPE_LABELS: Record<string, string> = {
+  TRANSPORT: 'Transport',
+  MEETING: 'Meeting',
+  EVENT: 'Event',
+  MEAL: 'Meal',
+  ACCOMMODATION: 'Accommodation',
+};
+
+export const EVENT_STATUS_LABELS: Record<string, string> = {
+  SCHEDULED: 'Scheduled',
+  IN_PROGRESS: 'In Progress',
+  COMPLETED: 'Completed',
+  CANCELLED: 'Cancelled',
+};
+
+/**
+ * Helper function to get a label for any enum value
+ * Falls back to the value itself if no mapping is found
+ */
+export function getEnumLabel(
+  value: string,
+  labels: Record<string, string>
+): string {
+  return labels[value] || value;
+}

frontend/src/lib/query-keys.ts

@@ -0,0 +1,93 @@
+/**
+ * Query key factory constants for TanStack Query
+ *
+ * This file provides typed, centralized query key management for all entities.
+ * Using factory functions ensures consistent keys across the application.
+ *
+ * @see https://tkdodo.eu/blog/effective-react-query-keys
+ */
+
+export const queryKeys = {
+  // VIPs
+  vips: {
+    all: ['vips'] as const,
+    detail: (id: string) => ['vip', id] as const,
+    forSchedule: (vipIds: string) => ['vips-for-schedule', vipIds] as const,
+  },
+
+  // Drivers
+  drivers: {
+    all: ['drivers'] as const,
+    myProfile: ['my-driver-profile'] as const,
+    schedule: (driverId: string, date: string) => ['driver-schedule', driverId, date] as const,
+  },
+
+  // Events/Schedule
+  events: {
+    all: ['events'] as const,
+  },
+
+  // Vehicles
+  vehicles: {
+    all: ['vehicles'] as const,
+  },
+
+  // Flights
+  flights: {
+    all: ['flights'] as const,
+    budget: ['flights', 'budget'] as const,
+  },
+
+  // Users
+  users: {
+    all: ['users'] as const,
+  },
+
+  // GPS/Location Tracking
+  gps: {
+    status: ['gps', 'status'] as const,
+    settings: ['gps', 'settings'] as const,
+    devices: ['gps', 'devices'] as const,
+    deviceQr: (driverId: string) => ['gps', 'devices', driverId, 'qr'] as const,
+    locations: {
+      all: ['gps', 'locations'] as const,
+      detail: (driverId: string) => ['gps', 'locations', driverId] as const,
+    },
+    stats: (driverId: string, from?: string, to?: string) =>
+      ['gps', 'stats', driverId, from, to] as const,
+    me: {
+      status: ['gps', 'me'] as const,
+      stats: (from?: string, to?: string) => ['gps', 'me', 'stats', from, to] as const,
+      location: ['gps', 'me', 'location'] as const,
+    },
+    traccar: {
+      status: ['gps', 'traccar', 'status'] as const,
+      adminUrl: ['gps', 'traccar', 'admin-url'] as const,
+    },
+  },
+
+  // Settings
+  settings: {
+    pdf: ['settings', 'pdf'] as const,
+    timezone: ['settings', 'timezone'] as const,
+  },
+
+  // Signal Messages
+  signal: {
+    messages: (driverId: string) => ['signal-messages', driverId] as const,
+    unreadCounts: ['signal-unread-counts'] as const,
+    driverResponses: (eventIds: string) => ['signal-driver-responses', eventIds] as const,
+    status: ['signal-status'] as const,
+    messageStats: ['signal-message-stats'] as const,
+  },
+
+  // Admin
+  admin: {
+    stats: ['admin-stats'] as const,
+  },
+
+  // Features
+  features: {
+    all: ['features'] as const,
+  },
+} as const;

frontend/src/lib/utils.ts

@@ -35,3 +35,18 @@ export function formatTime(date: string | Date, timeZone?: string): string {
     ...(timeZone && { timeZone }),
   });
 }
+
+/**
+ * Convert ISO datetime string to datetime-local input format (YYYY-MM-DDTHH:mm)
+ * Used for populating datetime-local inputs in forms
+ */
+export function toDatetimeLocal(isoString: string | null | undefined): string {
+  if (!isoString) return '';
+  const date = new Date(isoString);
+  const year = date.getFullYear();
+  const month = String(date.getMonth() + 1).padStart(2, '0');
+  const day = String(date.getDate()).padStart(2, '0');
+  const hours = String(date.getHours()).padStart(2, '0');
+  const minutes = String(date.getMinutes()).padStart(2, '0');
+  return `${year}-${month}-${day}T${hours}:${minutes}`;
+}