Add StartOS 0.4 package scaffold (manifest, main, interfaces, 2 actions)

- package/Makefile + s9pk.mk + package.json + tsconfig.json
- startos/manifest: dockerBuild source pointing at ../image/Dockerfile
- startos/main: reads /data/config.yaml reactively, passes env vars to container
- startos/interfaces: binds port 9999 as HTTP UI
- startos/actions: showPublicKey (read /data/ssh/id_ed25519.pub), configureSparks
- TS + JS bundle compile clean (tsc --noEmit, ncc build)

package/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "spark-control-startos",
+  "scripts": {
+    "build": "rm -rf ./javascript && ncc build startos/index.ts -o ./javascript",
+    "prettier": "prettier --write startos",
+    "check": "tsc --noEmit"
+  },
+  "dependencies": {
+    "@start9labs/start-sdk": "1.3.3"
+  },
+  "devDependencies": {
+    "@types/node": "^22.19.0",
+    "@vercel/ncc": "^0.38.4",
+    "prettier": "^3.6.2",
+    "typescript": "^5.9.3"
+  },
+  "prettier": {
+    "trailingComma": "all",
+    "tabWidth": 2,
+    "semi": false,
+    "singleQuote": true
+  }
+}