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/lib/imagehash.ts

@@ -4,6 +4,7 @@
 // hashes differ in few bits look alike to a person (and to a reviewer comparing store pages).
 import { readFileSync } from 'node:fs';
 import { inflateSync } from 'node:zlib';
+import * as rt from './rt';
 
 export interface Gray { w: number; h: number; px: Float64Array }
 
@@ -128,9 +129,9 @@ export function hashFile(path: string): { hash: ImageHash | null; reason?: strin
   try {
     const buf = readFileSync(path);
     if (buf.length > 8 && buf.readUInt32BE(0) === 0x89504e47) return { hash: hashGray(decodePng(buf)) };
-    const ffmpeg = Bun.which('ffmpeg');
+    const ffmpeg = rt.which('ffmpeg');
     if (!ffmpeg) return { hash: null, reason: 'not a PNG and ffmpeg is not installed' };
-    const r = Bun.spawnSync([ffmpeg, '-v', 'error', '-i', path, '-frames:v', '1', '-vf', 'scale=32:32:flags=area,format=gray', '-f', 'rawvideo', '-'], { stdout: 'pipe', stderr: 'pipe', timeout: 20_000 });
+    const r = rt.spawnSync([ffmpeg, '-v', 'error', '-i', path, '-frames:v', '1', '-vf', 'scale=32:32:flags=area,format=gray', '-f', 'rawvideo', '-'], { stdout: 'pipe', stderr: 'pipe', timeout: 20_000 });
     const px = r.stdout;
     if (r.exitCode !== 0 || px.length !== 1024) return { hash: null, reason: `ffmpeg could not read it (${r.stderr.toString().trim().split('\n')[0]?.slice(0, 120) ?? r.exitCode})` };
     return { hash: hashGray({ w: 32, h: 32, px: Float64Array.from(px) }) };