fix(model): use camelCase for session-project JSON tags

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: AnnatarHe

model/api_session_project.go

@@ -7,8 +7,8 @@ import (
 )
 
 type sessionProjectRequest struct {
-	SessionID   string `json:"session_id"`
-	ProjectPath string `json:"project_path"`
+	SessionID   string `json:"sessionId"`
+	ProjectPath string `json:"projectPath"`
 }
 
 type sessionProjectResponse struct{}