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>

backend/src/flights/flights.service.ts

@@ -4,6 +4,7 @@ import { ConfigService } from '@nestjs/config';
 import { PrismaService } from '../prisma/prisma.service';
 import { CreateFlightDto, UpdateFlightDto } from './dto';
 import { firstValueFrom } from 'rxjs';
+import { convertOptionalDates } from '../common/utils/date.utils';
 
 @Injectable()
 export class FlightsService {
@@ -24,17 +25,16 @@ export class FlightsService {
       `Creating flight: ${createFlightDto.flightNumber} for VIP ${createFlightDto.vipId}`,
     );
 
-    return this.prisma.flight.create({
-      data: {
+    const data = convertOptionalDates(
+      {
         ...createFlightDto,
         flightDate: new Date(createFlightDto.flightDate),
-        scheduledDeparture: createFlightDto.scheduledDeparture
-          ? new Date(createFlightDto.scheduledDeparture)
-          : undefined,
-        scheduledArrival: createFlightDto.scheduledArrival
-          ? new Date(createFlightDto.scheduledArrival)
-          : undefined,
       },
+      ['scheduledDeparture', 'scheduledArrival'],
+    );
+
+    return this.prisma.flight.create({
+      data,
       include: { vip: true },
     });
   }
@@ -71,24 +71,13 @@ export class FlightsService {
 
     this.logger.log(`Updating flight ${id}: ${flight.flightNumber}`);
 
-    const updateData: any = { ...updateFlightDto };
-    const dto = updateFlightDto as any; // Type assertion to work around PartialType
-
-    if (dto.flightDate) {
-      updateData.flightDate = new Date(dto.flightDate);
-    }
-    if (dto.scheduledDeparture) {
-      updateData.scheduledDeparture = new Date(dto.scheduledDeparture);
-    }
-    if (dto.scheduledArrival) {
-      updateData.scheduledArrival = new Date(dto.scheduledArrival);
-    }
-    if (dto.actualDeparture) {
-      updateData.actualDeparture = new Date(dto.actualDeparture);
-    }
-    if (dto.actualArrival) {
-      updateData.actualArrival = new Date(dto.actualArrival);
-    }
+    const updateData = convertOptionalDates(updateFlightDto, [
+      'flightDate',
+      'scheduledDeparture',
+      'scheduledArrival',
+      'actualDeparture',
+      'actualArrival',
+    ]);
 
     return this.prisma.flight.update({
       where: { id: flight.id },