fix(migrate): override vite-plus version for standalone projects in force-migrate mode

In `rewriteStandaloneProject`, when `VITE_PLUS_FORCE_MIGRATE=1`:
- The pnpm overrides didn't include `vite-plus` itself (only vite, vitest, etc.)
- The devDependency wasn't updated if `vite-plus` already existed

This caused ecosystem-ci to install the published `vite-plus@0.1.14` instead of
the local `vite-plus@0.0.0` tgz, failing the `verify-install.ts` check.

Closes #1177

Author: fengmk2

packages/cli/src/migration/migrator.ts

@@ -720,6 +720,7 @@ export function rewriteStandaloneProject(
         overrides: {
           ...pkg.pnpm?.overrides,
           ...VITE_PLUS_OVERRIDE_PACKAGES,
+          ...(isForceOverrideMode() ? { [VITE_PLUS_NAME]: VITE_PLUS_VERSION } : {}),
         },
       };
       // remove packages from `resolutions` field if they exist
@@ -734,7 +735,7 @@ export function rewriteStandaloneProject(
     extractedStagedConfig = rewritePackageJson(pkg, packageManager, false, skipStagedMigration);
 
     // ensure vite-plus is in devDependencies
-    if (!pkg.devDependencies?.[VITE_PLUS_NAME]) {
+    if (!pkg.devDependencies?.[VITE_PLUS_NAME] || isForceOverrideMode()) {
       pkg.devDependencies = {
         ...pkg.devDependencies,
         [VITE_PLUS_NAME]: VITE_PLUS_VERSION,