refactor: update bundler flag handling in create-next-app templates

Removed the default `--turbopack` flag from the development script in package.json, as Turbopack is now the default bundler in v16+. The `--webpack` flag is only added when explicitly using Webpack. Updated related tests to reflect this change.

Author: Nayeem-XTREME

packages/create-next-app/templates/index.ts

@@ -199,7 +199,9 @@ export const installTemplate = async ({
 
   /** Copy the version from package.json or override for tests. */
   const version = process.env.NEXT_PRIVATE_TEST_VERSION ?? pkg.version;
-  const bundlerFlags = `${bundler === Bundler.Turbopack ? " --turbopack" : ""}${bundler === Bundler.Webpack ? " --webpack" : ""}`;
+  // Turbopack is the default bundler in v16+, so no flag is needed
+  // Only add --webpack flag when explicitly using webpack
+  const bundlerFlags = bundler === Bundler.Webpack ? " --webpack" : "";
 
   /** Create a package.json for the new project and write it to disk. */
   const packageJson: any = {

test/integration/create-next-app/templates/app-api.test.ts

@@ -180,7 +180,7 @@ describe('create-next-app --api (Headless App)', () => {
         const projectRoot = join(cwd, projectName)
         const pkgJson = require(join(projectRoot, 'package.json'))
         // eslint-disable-next-line jest/no-standalone-expect
-        expect(pkgJson.scripts.dev).toBe('next dev --turbopack')
+        expect(pkgJson.scripts.dev).toBe('next dev')
 
         await tryNextDev({
           cwd,

test/integration/create-next-app/templates/app.test.ts

@@ -264,7 +264,7 @@ describe('create-next-app --app (App Router)', () => {
         const projectRoot = join(cwd, projectName)
         const pkgJson = require(join(projectRoot, 'package.json'))
         // eslint-disable-next-line jest/no-standalone-expect
-        expect(pkgJson.scripts.dev).toBe('next dev --turbopack')
+        expect(pkgJson.scripts.dev).toBe('next dev')
       })
     }
   )

test/integration/create-next-app/templates/pages.test.ts

@@ -275,7 +275,7 @@ describe('create-next-app --no-app (Pages Router)', () => {
         const projectRoot = join(cwd, projectName)
         const pkgJson = require(join(projectRoot, 'package.json'))
         // eslint-disable-next-line jest/no-standalone-expect
-        expect(pkgJson.scripts.dev).toBe('next dev --turbopack')
+        expect(pkgJson.scripts.dev).toBe('next dev')
       })
     }
   )