fix: add entry for vite prebundling scanner (#3169)

Author: bluwy

.changeset/quick-pets-turn.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Fix dev prebundling scanner

packages/kit/src/core/dev/index.js

@@ -61,6 +61,13 @@ export async function dev({ cwd, port, host, https, config }) {
 				$lib: config.kit.files.lib
 			}
 		},
+		build: {
+			rollupOptions: {
+				// Vite dependency crawler needs an explicit JS entry point
+				// eventhough server otherwise works without it
+				input: path.resolve(`${output}/runtime/internal/start.js`)
+			}
+		},
 		plugins: [
 			svelte({
 				extensions: config.extensions,