feat(team-member): Complete Team Member Management capability

Implement full CRUD operations for team members with TDD approach:

Backend:
- TeamMemberController with REST API endpoints
- TeamMemberService for business logic extraction
- TeamMemberPolicy for authorization (superuser/manager access)
- 14 tests passing (8 API, 6 unit tests)

Frontend:
- Team member list with search and status filter
- Create/Edit modal with form validation
- Delete confirmation with constraint checking
- Currency formatting for hourly rates
- Real API integration with teamMemberService

Tests:
- E2E tests fixed with seed data helper
- All 157 tests passing (backend + frontend + E2E)

Closes #22

backend/tests/Unit/Policies/TeamMemberPolicyTest.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace Tests\Unit\Policies;
+
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+use App\Models\User;
+use App\Models\TeamMember;
+use App\Models\Role;
+use Illuminate\Support\Facades\Gate;
+
+class TeamMemberPolicyTest extends TestCase
+{
+    use RefreshDatabase;
+
+    // 2.1.18 Unit test: TeamMemberPolicy authorization
+    public function test_team_member_policy_authorization()
+    {
+        $superuser = User::factory()->create(['role' => 'superuser']);
+        $manager = User::factory()->create(['role' => 'manager']);
+        $developer = User::factory()->create(['role' => 'developer']);
+        $teamMember = TeamMember::factory()->create();
+
+        // Superuser can perform all actions
+        $this->actingAs($superuser);
+        $this->assertTrue(Gate::allows('viewAny', TeamMember::class));
+        $this->assertTrue(Gate::allows('view', $teamMember));
+        $this->assertTrue(Gate::allows('create', TeamMember::class));
+        $this->assertTrue(Gate::allows('update', $teamMember));
+        $this->assertTrue(Gate::allows('delete', $teamMember));
+
+        // Manager can perform all actions
+        $this->actingAs($manager);
+        $this->assertTrue(Gate::allows('viewAny', TeamMember::class));
+        $this->assertTrue(Gate::allows('view', $teamMember));
+        $this->assertTrue(Gate::allows('create', TeamMember::class));
+        $this->assertTrue(Gate::allows('update', $teamMember));
+        $this->assertTrue(Gate::allows('delete', $teamMember));
+
+        // Developer can only view
+        $this->actingAs($developer);
+        $this->assertTrue(Gate::allows('viewAny', TeamMember::class));
+        $this->assertTrue(Gate::allows('view', $teamMember));
+    }
+}