fix: Export startBackendServer function and fix import issues

Author: SFARPak

src/ipc/handlers/chat_handlers.ts

@@ -188,7 +188,7 @@ export function registerChatHandlers() {
       throw new Error("App not found");
     }
 
-    const backendPath = getDyadAppPath(app.path, "backend");
+    const backendPath = path.join(getDyadAppPath(app.path), "backend");
 
     // Check if backend directory exists
     if (!fs.existsSync(backendPath)) {

src/ipc/handlers/createFromTemplate.ts

@@ -1647,7 +1647,7 @@ async function installDependenciesForFramework(projectPath: string, framework: s
   });
 }
 
-async function startBackendServer(projectPath: string, framework: string) {
+export async function startBackendServer(projectPath: string, framework: string) {
   const startCommand = getStartCommandForFramework(framework);
 
   return new Promise<void>((resolve, reject) => {