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/startos/interfaces.ts

@@ -0,0 +1,25 @@
+import { i18n } from './i18n'
+import { sdk } from './sdk'
+import { uiPort } from './utils'
+
+export const setInterfaces = sdk.setupInterfaces(async ({ effects }) => {
+  const uiMulti = sdk.MultiHost.of(effects, 'ui-multi')
+  const uiMultiOrigin = await uiMulti.bindPort(uiPort, {
+    protocol: 'http',
+  })
+  const ui = sdk.createInterface(effects, {
+    name: i18n('Web UI'),
+    id: 'ui',
+    description: i18n('The Spark Control web interface'),
+    type: 'ui',
+    masked: false,
+    schemeOverride: null,
+    username: null,
+    path: '',
+    query: {},
+  })
+
+  const uiReceipt = await uiMultiOrigin.export([ui])
+
+  return [uiReceipt]
+})