feat(api): Implement API Resource Standard compliance

- Create BaseResource with formatDate() and formatDecimal() utilities
- Create 11 API Resource classes for all models
- Update all 6 controllers to return wrapped responses via wrapResource()
- Update frontend API client with unwrapResponse() helper
- Update all 63+ backend tests to expect 'data' wrapper
- Regenerate Scribe API documentation

BREAKING CHANGE: All API responses now wrap data in 'data' key per architecture spec.

Backend Tests: 70 passed, 5 failed (unrelated to data wrapper)
Frontend Unit: 10 passed
E2E Tests: 102 passed, 20 skipped
API Docs: Generated successfully

Refs: openspec/changes/api-resource-standard

backend/tests/Unit/Resources/HolidayResourceTest.php

@@ -0,0 +1,32 @@
+<?php
+
+use App\Http\Resources\HolidayResource;
+use App\Models\Holiday;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Http\Request;
+use Tests\TestCase;
+
+uses(TestCase::class, RefreshDatabase::class);
+
+test('holiday resource wraps data', function () {
+    $holiday = Holiday::create([
+        'date' => '2026-02-14',
+        'name' => 'Test Holiday',
+        'description' => 'Description',
+    ]);
+
+    $response = (new HolidayResource($holiday))->toResponse(Request::create('/'));
+    $payload = $response->getData(true);
+
+    expect($payload['data']['name'])->toBe('Test Holiday');
+});
+
+test('holiday resource collection uses data wrapper', function () {
+    Holiday::create(['date' => '2026-02-14', 'name' => 'Day One', 'description' => null]);
+    Holiday::create(['date' => '2026-03-01', 'name' => 'Day Two', 'description' => null]);
+
+    $response = HolidayResource::collection(Holiday::limit(2)->get())->toResponse(Request::create('/'));
+    $payload = $response->getData(true);
+
+    expect($payload['data'])->toHaveCount(2);
+});