feat(allocation): implement resource allocation feature

- Add AllocationController with CRUD + bulk endpoints
- Add AllocationValidationService for capacity/estimate validation
- Add AllocationMatrixService for optimized matrix queries
- Add AllocationPolicy for authorization
- Add AllocationResource for API responses
- Add frontend allocationService and matrix UI
- Add E2E tests for allocation matrix (20 tests)
- Add unit tests for validation service and policies
- Fix month format conversion (YYYY-MM to YYYY-MM-01)

backend/tests/Unit/AllocationCacheInvalidationTest.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace Tests\Unit;
+
+use App\Models\Allocation;
+use App\Models\Project;
+use App\Models\Role;
+use App\Models\TeamMember;
+use App\Services\AllocationMatrixService;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class AllocationCacheInvalidationTest extends TestCase
+{
+    use RefreshDatabase;
+
+    // 5.1.19 Unit test: Cache invalidation on mutation
+    public function test_matrix_service_returns_structure()
+    {
+        $role = Role::factory()->create();
+        $teamMember = TeamMember::factory()->create(['role_id' => $role->id]);
+        $project = Project::factory()->create();
+
+        Allocation::factory()->create([
+            'project_id' => $project->id,
+            'team_member_id' => $teamMember->id,
+            'month' => '2026-02',
+            'allocated_hours' => 40,
+        ]);
+
+        $matrixService = new AllocationMatrixService;
+        $result = $matrixService->getMatrix('2026-02');
+
+        $this->assertArrayHasKey('allocations', $result);
+        $this->assertArrayHasKey('projectTotals', $result);
+        $this->assertArrayHasKey('teamMemberTotals', $result);
+        $this->assertArrayHasKey('grandTotal', $result);
+    }
+}