chore: remove unused packages, imports, and stale type definitions

- Remove @casl/prisma (unused) from backend
- Remove @heroicons/react (unused, using lucide-react) from frontend
- Remove unused InferSubjects import from ability.factory.ts
- Remove unused Calendar import from Dashboard.tsx
- Delete stale frontend/src/lib/types.ts (duplicate of src/types/index.ts)

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

backend/src/auth/abilities/ability.factory.ts

@@ -1,4 +1,4 @@
-import { AbilityBuilder, PureAbility, AbilityClass, ExtractSubjectType, InferSubjects } from '@casl/ability';
+import { AbilityBuilder, PureAbility, AbilityClass, ExtractSubjectType } from '@casl/ability';
 import { Injectable } from '@nestjs/common';
 import { Role, User, VIP, Driver, ScheduleEvent, Flight, Vehicle } from '@prisma/client';