fix(init): generate .void types on install in scaffolded starters (#521)

Fixes #519

Add `"postinstall": "void prepare"` to the starter scripts. Init
installs after writing the starter, so a new scaffold gets the types at
that point, and a fresh clone gets them on install. This is the same
approach as `nuxt prepare`.

`EMPTY_PROJECT_ALLOWED_SCRIPTS` also allows `postinstall: void prepare`,
so running init again on a starter still sees it as an empty project.

Checked:
- `init.test.ts` (`postinstall` in the React + D1 starter, and the
deleted-starter check)
- a 1.1.12 starter cloned fresh with `postinstall` added: `pnpm install`
creates `.void/db.d.ts` and `routes.d.ts`, and `tsc` passes (it fails
without it)

16 tests in `init.test.ts` fail locally on main too. This PR adds no new
failures.

Author: ashunar0

packages/void/src/cli/init.ts

@@ -241,6 +241,7 @@ const EMPTY_PROJECT_ALLOWED_SCRIPTS: Record<string, Set<string> | undefined> = {
   dev: new Set(['vite', 'vp dev']),
   build: new Set(['vite build', 'vp build']),
   preview: new Set(['vite preview', 'vp preview']),
+  postinstall: new Set(['void prepare']),
 };
 const EMPTY_PROJECT_STARTER_SCRIPT_COMMANDS = new Set(
   Object.values(EMPTY_PROJECT_ALLOWED_SCRIPTS).flatMap((commands) =>

packages/void/src/cli/template.ts

@@ -189,6 +189,9 @@ export function createPagesStarterTemplate(options: {
       dev: toolchain === 'vite-plus' ? 'vp dev' : 'vite',
       build: toolchain === 'vite-plus' ? 'vp build' : 'vite build',
       preview: toolchain === 'vite-plus' ? 'vp preview' : 'vite preview',
+      // `.void/` is gitignored, so fresh clones and new scaffolds need the
+      // generated types before the editor opens tsconfig.json.
+      postinstall: 'void prepare',
     },
     dependencies: {
       ...SCAFFOLD_BASE_DEPENDENCIES,

packages/void/test/unit/init.test.ts

@@ -1205,6 +1205,7 @@ describe('isScaffoldableEmptyProject', () => {
               dev: 'vp dev',
               build: 'vp build',
               preview: 'vp preview',
+              postinstall: 'void prepare',
             },
             dependencies: {
               hono: '^4.11.9',
@@ -1321,6 +1322,7 @@ describe('isScaffoldableEmptyProject', () => {
       expect(pkg.scripts.dev).toBe('vp dev');
       expect(pkg.scripts.build).toBe('vp build');
       expect(pkg.scripts.preview).toBe('vp preview');
+      expect(pkg.scripts.postinstall).toBe('void prepare');
 
       const reactViteConfig = readFileSync(join(root, 'vite.config.ts'), 'utf-8');
       expect(reactViteConfig).toContain('from "@void/react/plugin"');