CLI runs on Node 20+: npx storebound (bunx keeps working)

- cli/lib/rt.ts: the runtime layer on node: modules (spawn / spawnSync with Bun's defaults, exit codes and
  "Executable not found", which with PATHEXT, sleep, serve, Glob, hasher, gunzip, stdin, SQLite, packageRoot,
  config imports with a type-stripping fallback for Node 20); every Bun.* use in cli/ goes through it
- tools/gen-embedded.ts -> cli/lib/embedded.ts: templates/, cli/shots/*.html and Play's Data safety form embedded
  (replaces Bun text imports; the bundle and the compiled sidecar carry them), checked fresh by bun run ci
- package.json: bin dist/storebound.mjs (Node ESM bundle, tools/build-node.ts, prepack), engines node >=20
- bun run ci: node bundle + node smoke (real node: --version, help, check same as Bun, scan, release plan --help,
  init, MCP handshake + tool call); Forgejo CI sets up Node 20; tests/node-compat.test.ts guards cli/
- install writes npx MCP commands when run with Node; bin/storebound falls back to Node
- docs: npx storebound init (Node 20+) or bunx storebound init

cli/play/build.ts

@@ -26,6 +26,7 @@ import { capacitorProject, webStep } from '../lib/web-assets';
 import { androidSdk, androidSdkEnv, androidSdkMissing } from '../lib/tools';
 import { playClient } from './client';
 import { usedVersionCodes } from './next-version-code';
+import * as rt from '../lib/rt';
 
 const TAG = 'build';
 
@@ -93,7 +94,7 @@ export async function run(ctx: Ctx): Promise<void> {
   log(TAG, `$ ${plan.command}`);
   const started = Date.now();
   mkdirSync(out, { recursive: true });
-  const p = Bun.spawn(argv, { cwd, stdout: 'pipe', stderr: 'pipe', env: { ...process.env, ...androidSdkEnv(sdk), ...signingEnv(signing) } });
+  const p = rt.spawn(argv, { cwd, stdout: 'pipe', stderr: 'pipe', env: { ...process.env, ...androidSdkEnv(sdk), ...signingEnv(signing) } });
   const lines: string[] = [];
   const each = (line: string): void => {
     lines.push(line);