feat(backend): enhance allocation and project management

Update controllers and services for allocation fidelity:
- AllocationController: variance data in responses, bulk operations
- ProjectController: include plan data in responses
- ProjectMonthPlanController: planning grid API
- AllocationMatrixService: support untracked allocations
- ProjectResource/TeamMemberResource: include reconciliation data

Improved test coverage for allocation flows.

backend/app/Http/Controllers/Api/RolesController.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace App\Http\Controllers\Api;
+
+use App\Http\Controllers\Controller;
+use App\Http\Resources\RoleResource;
+use App\Models\Role;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+
+/**
+ * @group Roles
+ *
+ * Endpoints for managing roles.
+ */
+class RolesController extends Controller
+{
+    /**
+     * List all roles
+     *
+     * Get a list of all available roles for team members.
+     *
+     * @authenticated
+     *
+     * @response 200 {
+     *   "data": [
+     *     {
+     *       "id": 1,
+     *       "name": "Frontend Dev",
+     *       "description": "Frontend Developer - specializes in UI/UX and client-side development"
+     *     }
+     *   ]
+     * }
+     */
+    public function index(Request $request): JsonResponse
+    {
+        $roles = Role::orderBy('name')->get(['id', 'name', 'description']);
+
+        return $this->wrapResource(RoleResource::collection($roles));
+    }
+}