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/.scribe/endpoints.cache/00.yaml

@@ -62,16 +62,19 @@ endpoints:
         status: 200
         content: |-
           {
-            "access_token": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9...",
-            "refresh_token": "abc123def456",
-            "token_type": "bearer",
-            "expires_in": 3600,
-            "user": {
+            "data": {
               "id": "550e8400-e29b-41d4-a716-446655440000",
               "name": "Alice Johnson",
               "email": "user@example.com",
-              "role": "manager"
-            }
+              "role": "manager",
+              "active": true,
+              "created_at": "2026-01-01T00:00:00Z",
+              "updated_at": "2026-01-01T00:00:00Z"
+            },
+            "access_token": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9...",
+            "refresh_token": "abc123def456",
+            "token_type": "bearer",
+            "expires_in": 3600
           }
         headers: []
         description: ''
@@ -143,6 +146,15 @@ endpoints:
         status: 200
         content: |-
           {
+            "data": {
+              "id": "550e8400-e29b-41d4-a716-446655440000",
+              "name": "Alice Johnson",
+              "email": "user@example.com",
+              "role": "manager",
+              "active": true,
+              "created_at": "2026-01-01T00:00:00Z",
+              "updated_at": "2026-01-01T00:00:00Z"
+            },
             "access_token": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9...",
             "refresh_token": "newtoken123",
             "token_type": "bearer",