docs(errors): 사이트 docs 전체에서 옛 명명 흔적 제거 (영/한, 53개 파일)

Phase 1(직전 커밋)에서 튜토리얼 13/14/15/16 self-contained framework를
정렬했고, 이번 커밋은 Docs.Site 전체로 범위를 넓혀 산문·예시·로그
샘플에 잔존하던 옛 명명을 모두 신규 1.0.0-alpha.4+ 기준으로 통일.

Cat B (산문 옛 type/factory 이름):
- spec/04-error-system.md (영/한): 마이그레이션 매핑 표를 제거하고
  "릴리스 노트 참조" 한 줄로 단축. spec 본문에 옛 이름 노출 금지 정책.

Cat C (옛 prefix DomainErrors.X.Y → Domain.X.Y):
- guides/{adapter,application,domain,observability}/*.md
- spec/03-validation.md, spec/06-port-adapter.md, spec/07-pipeline.md
- adr/0003-domain-cqrs-read-write-separation.md
- tutorials/{architecture-rules,cqrs-repository,functional-valueobject,
  specification-pattern}/...
- samples/{ai-model-governance,designing-with-types,ecommerce-ddd}/...
- getting-started.mdx, key-features.mdx, index.mdx, quickstart, etc.
- 영/한 동시 갱신, 약 51개 파일

치환 규칙:
- DomainErrors.\([A-Z]\) → Domain.\1 (대문자 시작 클래스명만 매칭하여
  사용자 정의 static class 메서드 호출과 framework prefix 출력 분리)
- 동일 패턴 ApplicationErrors / AdapterErrors

코드 변경 0. 검증: grep 잔존 0건.

후속 별도 작업: 일부 튜토리얼(.md 본문)은 사용자 정의 static class
DomainErrors 패턴을 인용하지만 짝이 되는 .cs는 framework helper
DomainError.For<T>() 패턴을 사용한다. 이 .md ↔ .cs 동기화는 본문
재작성이 필요하므로 별도 PR로 분리.

Author: hhko

Docs.Site/src/content/docs/getting-started.mdx

@@ -66,7 +66,7 @@ public sealed partial class Email : SimpleValueObject<string>
 }
 ```
 
-The `Create` method returns `Fin<Email>`. For valid input, an `Email` instance is returned; for invalid input, a structured error code (such as `DomainErrors.Email.Empty`) is returned. No exceptions are thrown.
+The `Create` method returns `Fin<Email>`. For valid input, an `Email` instance is returned; for invalid input, a structured error code (such as `Domain.Email.Empty`) is returned. No exceptions are thrown.
 
 For detailed Value Object implementation patterns, see the [Value Objects Guide](/Functorium/guides/domain/05a-value-objects/).
 

Docs.Site/src/content/docs/guides/adapter/12-ports.md

@@ -742,7 +742,7 @@ email.IfSucc(e => Console.WriteLine(e));  // user@example.com
 
 // Failure
 var invalid = Email.Create("invalid-email");
-invalid.IfFail(e => Console.WriteLine(e.Code));  // DomainErrors.Email.InvalidFormat
+invalid.IfFail(e => Console.WriteLine(e.Code));  // Domain.Email.InvalidFormat
 ```
 
 ### Test Example

Docs.Site/src/content/docs/guides/domain/04-ddd-tactical-overview.md

@@ -814,7 +814,7 @@ using Functorium.Domains.ValueObjects.Validations.Contextual;
 
 // Named Context validation start
 ValidationRules.For("ProductName").NotEmpty(name);
-// Error: DomainErrors.ProductName.Empty
+// Error: Domain.ProductName.Empty
 
 // Chaining
 ValidationRules.For("OrderValidation")
@@ -889,12 +889,12 @@ public sealed class OrderValidation : IValidationContext;
 // 2. Use in ValidationRules<T> instead of a Value Object
 public Validation<Error, decimal> ValidatePrice(decimal price) =>
     ValidationRules<ProductValidation>.Positive(price);
-// Error Code: DomainErrors.ProductValidation.NotPositive
+// Error Code: Domain.ProductValidation.NotPositive
 
 public Validation<Error, string> ValidateOrderId(string orderId) =>
     ValidationRules<OrderValidation>.NotEmpty(orderId)
         .ThenMinLength(10);
-// Error Code: DomainErrors.OrderValidation.Empty or TooShort
+// Error Code: Domain.OrderValidation.Empty or TooShort
 ```
 
 **Advantages:**

Docs.Site/src/content/docs/guides/domain/05a-value-objects.md

@@ -622,7 +622,7 @@ Used inside a Value Object class, the type is determined at compile time.
 // Inside the Price class
 public static Validation<Error, decimal> Validate(decimal value) =>
     ValidationRules<Price>.Positive(value);
-// Error code: DomainErrors.Price.NotPositive
+// Error code: Domain.Price.NotPositive
 ```
 
 **ValidationRules.For() gets context from a "string."**
@@ -632,7 +632,7 @@ Used when there is no Value Object (DTO validation, API input validation).
 ```csharp
 // In DTO validation
 var result = ValidationRules.For("ProductPrice").Positive(request.Price);
-// Error code: DomainErrors.ProductPrice.NotPositive
+// Error code: Domain.ProductPrice.NotPositive
 ```
 
 **When to use which?**

Docs.Site/src/content/docs/guides/domain/05b-value-objects-validation.md

@@ -1000,7 +1000,7 @@ info: adapter event PublishTrackedEvents.PublishTrackedEvents responded success
 info: adapter event PublishTrackedEvents.PublishTrackedEvents requesting with 1 events
 info: application usecase.event OnProductCreated.Handle ProductCreatedEvent 01J1234567890ABCDEFGHJKMNP requesting with {@request.message}
 fail: application usecase.event OnProductCreated.Handle ProductCreatedEvent 01J1234567890ABCDEFGHJKMNP responded failure in 0.0008 s with exceptional:InvalidOperationException
-fail: adapter event PublishTrackedEvents.PublishTrackedEvents responded failure in 0.0309 s with 1 events with exceptional:ApplicationErrors.DomainEventPublisher.PublishFailed {@error}
+fail: adapter event PublishTrackedEvents.PublishTrackedEvents responded failure in 0.0309 s with 1 events with exceptional:Application.DomainEventPublisher.PublishFailed {@error}
 ```
 
 > **Note:** The `error.code` for exceptions from the Handler is the exception type name (`InvalidOperationException`), while the Publisher records a wrapped error code (`Application.DomainEventPublisher.PublishFailed`).
@@ -1011,7 +1011,7 @@ Adapter exceptions occur in the Repository, so they do not reach event publishin
 
 ```
 fail: adapter repository InMemoryProductRepository.Create responded failure in 0.0005 s with exceptional:Exceptional {@error}
-fail: application usecase.command CreateProductCommand.Handle responded failure in 0.0031 s with exceptional:AdapterErrors.UsecaseExceptionPipeline`2.PipelineException {@error}
+fail: application usecase.command CreateProductCommand.Handle responded failure in 0.0031 s with exceptional:Adapter.UsecaseExceptionPipeline`2.PipelineException {@error}
 ```
 
 ### IDomainEventCtxEnricher\<TEvent\> -- Event Handler Log Enrichment