feat(cms,asset): add comprehensive test suite and finalize modules

- Add comprehensive test suite for CMS and Asset modules using Pest Framework
- Implement ContentTypeService::delete() protection against deletion of in-use content types
- Add CannotDeleteContentTypeInUseException for better error handling
- Fix DerivatPipelineRegistry::getAllPipelines() to handle object uniqueness correctly
- Fix VariantName::getScale() to correctly parse scales with file extensions
- Update CMS module documentation with new features, exceptions, and test coverage
- Add CmsTestHelpers and AssetTestHelpers for test data factories
- Fix BlockTypeRegistry to be immutable after construction
- Update ContentTypeService to check for associated content before deletion
- Improve BlockRendererRegistry initialization

Test coverage:
- Value Objects: All CMS and Asset value objects
- Services: ContentService, ContentTypeService, SlugGenerator, BlockValidator, ContentLocalizationService, AssetService, DeduplicationService, MetadataExtractor
- Repositories: All database repositories with mocked connections
- Rendering: Block renderers and ContentRenderer
- Controllers: API endpoints for both modules

254 tests passing, 38 remaining (mostly image processing pipeline tests)

tests/Unit/Domain/Asset/ValueObjects/AssetIdTest.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Domain\Asset\ValueObjects\AssetId;
+use App\Framework\DateTime\SystemClock;
+
+describe('AssetId', function () {
+    it('can be created from valid ULID string', function () {
+        $validUlid = '01ARZ3NDEKTSV4RRFFQ69G5FAV';
+        $assetId = AssetId::fromString($validUlid);
+
+        expect($assetId->toString())->toBe($validUlid);
+        expect((string) $assetId)->toBe($validUlid);
+    });
+
+    it('throws exception for invalid ULID format', function () {
+        expect(fn () => AssetId::fromString('invalid-id'))
+            ->toThrow(InvalidArgumentException::class, 'Invalid Asset ID format');
+    });
+
+    it('can generate new AssetId with Clock', function () {
+        $clock = new SystemClock();
+        $assetId = AssetId::generate($clock);
+
+        expect($assetId)->toBeInstanceOf(AssetId::class);
+        expect($assetId->toString())->toMatch('/^[0-9A-Z]{26}$/');
+    });
+
+    it('generates unique IDs', function () {
+        $clock = new SystemClock();
+        $id1 = AssetId::generate($clock);
+        $id2 = AssetId::generate($clock);
+
+        expect($id1->toString())->not->toBe($id2->toString());
+    });
+
+    it('can compare two AssetIds for equality', function () {
+        $id1 = AssetId::fromString('01ARZ3NDEKTSV4RRFFQ69G5FAV');
+        $id2 = AssetId::fromString('01ARZ3NDEKTSV4RRFFQ69G5FAV');
+        $id3 = AssetId::fromString('01ARZ3NDEKTSV4RRFFQ69G5FAW');
+
+        expect($id1->equals($id2))->toBeTrue();
+        expect($id1->equals($id3))->toBeFalse();
+    });
+});
+