fix: allow resolving bare specifiers to relative paths for entries (#20379)

Author: sapphi-red

packages/vite/src/node/optimizer/scan.ts

@@ -237,6 +237,7 @@ async function computeEntries(environment: ScanEnvironment) {
           p,
           path.join(process.cwd(), '*'),
           {
+            isEntry: true,
             scan: true,
           },
         )

packages/vite/src/node/plugins/resolve.ts

@@ -254,7 +254,9 @@ export function resolvePlugin(
       // relative
       if (
         id[0] === '.' ||
-        ((preferRelative || importer?.endsWith('.html')) &&
+        ((preferRelative ||
+          resolveOpts.isEntry ||
+          importer?.endsWith('.html')) &&
           startsWithWordCharRE.test(id))
       ) {
         const basedir = importer ? path.dirname(importer) : process.cwd()