refactor: 将 OpType 字段从枚举类型改为 string 类型

主要变更：
- Operation.OpType: Type → string
- NewFullOperation 参数: opType Type → opType string
- IsValidOpType 参数: opType Type → opType string
- operationMeta.OpType: *Type → *string
- queryclient.ListRequest.OpType: model.Type → string

优点：
- 更灵活，支持动态扩展操作类型
- 不再受限于预定义的枚举常量
- 简化类型转换逻辑

兼容性：
- Type 常量定义保持不变 (OpTypeCreate, OpTypeUpdate 等)
- 使用时需要 string() 转换: string(model.OpTypeCreate)
- 所有单元测试已更新并通过 (100%)

测试结果：
✅ api/adapter - PASS
✅ api/highclient - PASS
✅ api/logger - PASS
✅ api/model - PASS
✅ api/persistence - PASS
✅ api/queryclient - PASS
✅ internal/* - PASS

api/model/operation_test.go

@@ -34,7 +34,7 @@ func TestOperation_CheckAndInit(t *testing.T) {
 			op: &model.Operation{
 				Timestamp:    time.Now(),
 				OpSource:     model.OpSourceIRP,
-				OpType:       model.OpTypeOCCreateHandle,
+				OpType:       string(model.OpTypeOCCreateHandle),
 				DoPrefix:     "test",
 				DoRepository: "repo",
 				Doid:         "test/repo/123",
@@ -48,7 +48,7 @@ func TestOperation_CheckAndInit(t *testing.T) {
 				OpID:         "", // Will be auto-generated
 				Timestamp:    time.Now(),
 				OpSource:     model.OpSourceIRP,
-				OpType:       model.OpTypeOCCreateHandle,
+				OpType:       string(model.OpTypeOCCreateHandle),
 				DoPrefix:     "test",
 				DoRepository: "repo",
 				Doid:         "test/repo/123",
@@ -62,7 +62,7 @@ func TestOperation_CheckAndInit(t *testing.T) {
 				OpID:         "op-123",
 				Timestamp:    time.Now(),
 				OpSource:     model.OpSourceIRP,
-				OpType:       model.OpTypeOCCreateHandle,
+				OpType:       string(model.OpTypeOCCreateHandle),
 				DoPrefix:     "test",
 				DoRepository: "repo",
 				Doid:         "test/repo/123",
@@ -77,7 +77,7 @@ func TestOperation_CheckAndInit(t *testing.T) {
 				OpID:         "op-123",
 				Timestamp:    time.Now(),
 				OpSource:     model.OpSourceIRP,
-				OpType:       model.OpTypeOCCreateHandle,
+				OpType:       string(model.OpTypeOCCreateHandle),
 				DoPrefix:     "test",
 				DoRepository: "repo",
 				Doid:         "invalid/123", // Doesn't start with "test/repo"
@@ -222,7 +222,7 @@ func TestOperation_MarshalUnmarshalBinary(t *testing.T) {
 		OpID:         "op-123",
 		Timestamp:    time.Now(),
 		OpSource:     model.OpSourceIRP,
-		OpType:       model.OpTypeOCCreateHandle,
+		OpType:       string(model.OpTypeOCCreateHandle),
 		DoPrefix:     "test",
 		DoRepository: "repo",
 		Doid:         "test/repo/123",
@@ -260,7 +260,7 @@ func TestOperation_MarshalBinary_Empty(t *testing.T) {
 	op := &model.Operation{
 		Timestamp:    time.Now(),
 		OpSource:     model.OpSourceIRP,
-		OpType:       model.OpTypeOCCreateHandle,
+		OpType:       string(model.OpTypeOCCreateHandle),
 		DoPrefix:     "test",
 		DoRepository: "repo",
 		Doid:         "test/repo/123",
@@ -297,7 +297,7 @@ func TestOperation_DoHash(t *testing.T) {
 		OpID:         "op-123",
 		Timestamp:    time.Now(),
 		OpSource:     model.OpSourceIRP,
-		OpType:       model.OpTypeOCCreateHandle,
+		OpType:       string(model.OpTypeOCCreateHandle),
 		DoPrefix:     "test",
 		DoRepository: "repo",
 		Doid:         "test/repo/123",
@@ -324,7 +324,7 @@ func TestOperationHashData(t *testing.T) {
 		OpID:         "op-123",
 		Timestamp:    time.Now(),
 		OpSource:     model.OpSourceIRP,
-		OpType:       model.OpTypeOCCreateHandle,
+		OpType:       string(model.OpTypeOCCreateHandle),
 		DoPrefix:     "test",
 		DoRepository: "repo",
 		Doid:         "test/repo/123",
@@ -362,7 +362,7 @@ func TestOperation_MarshalTrustlog_EmptyProducerID(t *testing.T) {
 		OpID:         "op-123",
 		Timestamp:    time.Now(),
 		OpSource:     model.OpSourceIRP,
-		OpType:       model.OpTypeOCCreateHandle,
+		OpType:       string(model.OpTypeOCCreateHandle),
 		DoPrefix:     "test",
 		DoRepository: "repo",
 		Doid:         "test/repo/123",
@@ -388,7 +388,7 @@ func TestOperation_MarshalTrustlog_NilSigner(t *testing.T) {
 		OpID:         "op-123",
 		Timestamp:    time.Now(),
 		OpSource:     model.OpSourceIRP,
-		OpType:       model.OpTypeOCCreateHandle,
+		OpType:       string(model.OpTypeOCCreateHandle),
 		DoPrefix:     "test",
 		DoRepository: "repo",
 		Doid:         "test/repo/123",
@@ -452,37 +452,37 @@ func TestIsValidOpType(t *testing.T) {
 	tests := []struct {
 		name     string
 		source   model.Source
-		opType   model.Type
+		opType   string
 		expected bool
 	}{
 		{
 			name:     "IRP有效操作类型",
 			source:   model.OpSourceIRP,
-			opType:   model.OpTypeOCCreateHandle,
+			opType:   string(model.OpTypeOCCreateHandle),
 			expected: true,
 		},
 		{
 			name:     "IRP无效操作类型",
 			source:   model.OpSourceIRP,
-			opType:   model.OpTypeHello,
+			opType:   string(model.OpTypeHello),
 			expected: false,
 		},
 		{
 			name:     "DOIP有效操作类型",
 			source:   model.OpSourceDOIP,
-			opType:   model.OpTypeHello,
+			opType:   string(model.OpTypeHello),
 			expected: true,
 		},
 		{
 			name:     "DOIP无效操作类型",
 			source:   model.OpSourceDOIP,
-			opType:   model.OpTypeOCCreateHandle,
+			opType:   string(model.OpTypeOCCreateHandle),
 			expected: false,
 		},
 		{
 			name:     "未知来源和类型",
 			source:   model.Source("unknown"),
-			opType:   model.Type("unknown"),
+			opType:   "unknown",
 			expected: false,
 		},
 	}
@@ -502,7 +502,7 @@ func TestNewFullOperation(t *testing.T) {
 	tests := []struct {
 		name         string
 		opSource     model.Source
-		opType       model.Type
+		opType       string
 		doPrefix     string
 		doRepository string
 		doid         string
@@ -516,7 +516,7 @@ func TestNewFullOperation(t *testing.T) {
 		{
 			name:         "成功创建完整操作",
 			opSource:     model.OpSourceIRP,
-			opType:       model.OpTypeOCCreateHandle,
+			opType:       string(model.OpTypeOCCreateHandle),
 			doPrefix:     "test",
 			doRepository: "repo",
 			doid:         "test/repo/123",
@@ -530,7 +530,7 @@ func TestNewFullOperation(t *testing.T) {
 		{
 			name:         "空请求体和响应体",
 			opSource:     model.OpSourceIRP,
-			opType:       model.OpTypeOCCreateHandle,
+			opType:       string(model.OpTypeOCCreateHandle),
 			doPrefix:     "test",
 			doRepository: "repo",
 			doid:         "test/repo/123",
@@ -544,7 +544,7 @@ func TestNewFullOperation(t *testing.T) {
 		{
 			name:         "字符串类型的请求体",
 			opSource:     model.OpSourceIRP,
-			opType:       model.OpTypeOCCreateHandle,
+			opType:       string(model.OpTypeOCCreateHandle),
 			doPrefix:     "test",
 			doRepository: "repo",
 			doid:         "test/repo/123",