feat: shift assignment workflow with claim, approve, reject, cancel, and bulk approve

Implements the complete ShiftAssignment lifecycle:
- ShiftAssignmentStatus enum with allowed transitions
- ShiftAssignmentService with claim/assign/approve/reject/cancel/bulkApprove
- ShiftAssignmentController with event-scoped endpoints
- ShiftAssignmentPolicy (organizer + volunteer self-cancel)
- VolunteerAvailability model, controller, and sync endpoint
- Refactored ShiftController to delegate to service layer
- 31 workflow tests covering all paths and multi-tenancy

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

api/app/Http/Controllers/Api/V1/ShiftAssignmentController.php

@@ -0,0 +1,101 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Controllers\Api\V1;
+
+use App\Enums\ShiftAssignmentStatus;
+use App\Http\Controllers\Controller;
+use App\Http\Requests\Api\V1\BulkApproveShiftAssignmentRequest;
+use App\Http\Requests\Api\V1\RejectShiftAssignmentRequest;
+use App\Http\Resources\Api\V1\ShiftAssignmentResource;
+use App\Models\Event;
+use App\Models\ShiftAssignment;
+use App\Services\ShiftAssignmentService;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+use Illuminate\Http\Resources\Json\AnonymousResourceCollection;
+use Illuminate\Support\Facades\Gate;
+
+final class ShiftAssignmentController extends Controller
+{
+    public function __construct(
+        private readonly ShiftAssignmentService $service,
+    ) {}
+
+    public function index(Request $request, Event $event): AnonymousResourceCollection
+    {
+        Gate::authorize('viewAny', [ShiftAssignment::class, $event]);
+
+        $query = ShiftAssignment::query()
+            ->whereHas('shift.festivalSection', fn ($q) => $q->where('event_id', $event->id))
+            ->with(['person', 'shift.festivalSection', 'shift.timeSlot']);
+
+        if ($request->filled('status')) {
+            $status = ShiftAssignmentStatus::tryFrom($request->string('status')->toString());
+            if ($status !== null) {
+                $query->where('status', $status);
+            }
+        }
+
+        if ($request->filled('shift_id')) {
+            $query->where('shift_id', $request->string('shift_id')->toString());
+        }
+
+        if ($request->filled('person_id')) {
+            $query->where('person_id', $request->string('person_id')->toString());
+        }
+
+        if ($request->filled('section_id')) {
+            $query->whereHas('shift', fn ($q) => $q->where('festival_section_id', $request->string('section_id')->toString()));
+        }
+
+        $assignments = $query->orderByDesc('created_at')->paginate(50);
+
+        return ShiftAssignmentResource::collection($assignments);
+    }
+
+    public function approve(Event $event, ShiftAssignment $shiftAssignment): JsonResponse
+    {
+        Gate::authorize('approve', [$shiftAssignment, $event]);
+
+        $shiftAssignment = $this->service->approve($shiftAssignment, request()->user());
+
+        return $this->success(new ShiftAssignmentResource($shiftAssignment->load(['person', 'shift.festivalSection', 'shift.timeSlot'])));
+    }
+
+    public function reject(RejectShiftAssignmentRequest $request, Event $event, ShiftAssignment $shiftAssignment): JsonResponse
+    {
+        Gate::authorize('reject', [$shiftAssignment, $event]);
+
+        $shiftAssignment = $this->service->reject(
+            $shiftAssignment,
+            $request->user(),
+            $request->validated('reason'),
+        );
+
+        return $this->success(new ShiftAssignmentResource($shiftAssignment->load(['person', 'shift.festivalSection', 'shift.timeSlot'])));
+    }
+
+    public function cancel(Event $event, ShiftAssignment $shiftAssignment): JsonResponse
+    {
+        Gate::authorize('cancel', [$shiftAssignment, $event]);
+
+        $shiftAssignment = $this->service->cancel($shiftAssignment, request()->user());
+
+        return $this->success(new ShiftAssignmentResource($shiftAssignment->load(['person', 'shift.festivalSection', 'shift.timeSlot'])));
+    }
+
+    public function bulkApprove(BulkApproveShiftAssignmentRequest $request, Event $event): JsonResponse
+    {
+        Gate::authorize('bulkApprove', [ShiftAssignment::class, $event]);
+
+        $assignments = ShiftAssignment::whereIn('id', $request->validated('assignment_ids'))
+            ->with('shift')
+            ->get();
+
+        $results = $this->service->bulkApprove($assignments, $request->user());
+
+        return $this->success($results);
+    }
+}