feat(examples): build flappy-bird as a self-contained single file (#223)

flappy-bird's end goal is a distributable binary; as a stepping stone it
builds a single dist/game.mjs that `node` runs on its own, with no
node_modules present. It's the example that demonstrates that ideal.

Bundle everything that CAN be bundled — vue, chalk, @vue-tui/runtime, yoga's
base64-inlined wasm, the SFC — and externalize ONLY Node builtins:

- The external predicate is `(id) => isBuiltin(id)`, inline in vite.config.ts
  (no separate file for a one-liner). It has no relative/absolute path
  heuristics, so the Windows path footgun behind vue-tui#209 can't exist here.
- rollupOptions.platform = "node" so rolldown emits a real
  createRequire(import.meta.url) for a CJS dep's require() instead of a stub
  that throws at startup (stack-utils does `require("module").builtinModules`
  at module load — the #212 fault class).

Guard the property that actually matters in examples-smoke: build flappy-bird,
copy ONLY game.mjs into a fresh temp dir with no node_modules, and launch it
there — it must paint. Verified red->green: dropping platform:"node" brings
back the throwing require shim (build-shim check fails) and re-externalizing a
dep is ERR_MODULE_NOT_FOUND in the empty sandbox.

Closes #209. Supersedes #210 (which targeted the now-removed @vue-tui/cli).

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

examples/flappy-bird/vite.config.ts

@@ -1,12 +1,18 @@
 import { defineConfig } from "vite";
 import vue from "@vitejs/plugin-vue";
 import { fileURLToPath } from "node:url";
+import { isBuiltin } from "node:module";
 
 const here = fileURLToPath(new URL(".", import.meta.url));
 
-// Build the example as a Node ESM bundle. SFCs are compiled by
-// @vitejs/plugin-vue; runtime deps (vue, @vue-tui/runtime, chalk, …) stay
-// external so Node resolves them from node_modules at startup.
+// Build the example as a SELF-CONTAINED Node ESM bundle: a single dist/game.mjs that `node` runs
+// with no node_modules present (the stepping stone toward a distributable binary). Bundle EVERYTHING
+// that can be bundled (vue, chalk, @vue-tui/runtime, yoga's base64-inlined wasm, the SFC) and
+// externalize ONLY Node's own builtins — isBuiltin() matches both "node:fs" and bare "fs". A
+// builtins-only rule has no relative/absolute path heuristics, so the Windows path footgun behind
+// vue-tui#209 can't exist here. `platform: "node"` makes rolldown emit a real
+// createRequire(import.meta.url) for a CJS dep's require() instead of a stub that throws at startup
+// (stack-utils does `require("module").builtinModules` at module load — the #212 fault class).
 export default defineConfig({
   plugins: [vue()],
   build: {
@@ -19,10 +25,10 @@ export default defineConfig({
       formats: ["es"],
       fileName: () => "game.mjs",
     },
-    rollupOptions: {
-      // Bundle anything resolved as a relative / absolute path (the .vue
-      // file + its `?vue` virtual modules); externalize bare specifiers.
-      external: (id) => !id.startsWith(".") && !id.startsWith("/") && !id.startsWith("\0"),
+    // Vite 8 is Rolldown-powered: rolldownOptions is the field (rollupOptions is the deprecated alias).
+    rolldownOptions: {
+      platform: "node",
+      external: (id) => isBuiltin(id),
     },
   },
 });