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/app/Http/Resources/PtoResource.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace App\Http\Resources;
+
+class PtoResource extends BaseResource
+{
+    public function toArray($request): array
+    {
+        return [
+            'id' => $this->id,
+            'team_member_id' => $this->team_member_id,
+            'team_member' => $this->whenLoaded('teamMember', fn () => new TeamMemberResource($this->teamMember)),
+            'start_date' => $this->start_date?->toDateString(),
+            'end_date' => $this->end_date?->toDateString(),
+            'reason' => $this->reason,
+            'status' => $this->status,
+            'created_at' => $this->formatDate($this->created_at),
+        ];
+    }
+}