fix(test): 修复测试和添加数据库迁移

测试修复：
- 修复集成测试中的重复键冲突问题
- 移除 JSON 中多余的尾随逗号
- 新增 inprocess_transport_test.go
- 更新 haiku 模型映射测试用例

数据库迁移：
- 026: 运营指标聚合表
- 027: 使用量与计费一致性约束

backend/internal/repository/claude_usage_service_test.go

@@ -33,7 +33,7 @@ type usageRequestCapture struct {
 func (s *ClaudeUsageServiceSuite) TestFetchUsage_Success() {
 	var captured usageRequestCapture
 
-	s.srv = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	s.srv = newLocalTestServer(s.T(), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		captured.authorization = r.Header.Get("Authorization")
 		captured.anthropicBeta = r.Header.Get("anthropic-beta")
 
@@ -59,7 +59,7 @@ func (s *ClaudeUsageServiceSuite) TestFetchUsage_Success() {
 }
 
 func (s *ClaudeUsageServiceSuite) TestFetchUsage_NonOK() {
-	s.srv = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	s.srv = newLocalTestServer(s.T(), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusUnauthorized)
 		_, _ = io.WriteString(w, "nope")
 	}))
@@ -73,7 +73,7 @@ func (s *ClaudeUsageServiceSuite) TestFetchUsage_NonOK() {
 }
 
 func (s *ClaudeUsageServiceSuite) TestFetchUsage_BadJSON() {
-	s.srv = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	s.srv = newLocalTestServer(s.T(), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/json")
 		_, _ = io.WriteString(w, "not-json")
 	}))
@@ -86,7 +86,7 @@ func (s *ClaudeUsageServiceSuite) TestFetchUsage_BadJSON() {
 }
 
 func (s *ClaudeUsageServiceSuite) TestFetchUsage_ContextCancel() {
-	s.srv = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	s.srv = newLocalTestServer(s.T(), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// Never respond - simulate slow server
 		<-r.Context().Done()
 	}))