refactor(examples): standardize devframe tool examples to app/ + src/node/ + playgrounds/

Apply the built-in plugin layout to the five examples that define a devframe:
- files-inspector, streaming-chat (Preact): app/ = SPA, src/node/ = definition + rpc,
  playgrounds/ boots the built tool; dev serves the app with HMR + a live node bridge,
  play builds then runs the playground
- sse-basic: extract the inline definition into src/node/, move the client into app/,
  keep the SSE-only bridge; add dev/play
- next-runtime-snapshot (Next): app/ = the Next app, src/node/ = definition + rpc,
  scripts/build-spa.mjs uses a mode-explicit recursive copy; add playgrounds/ + play
- json-render (no own SPA, reuses the prebuilt UI): consolidate the definition, dashboard,
  and shared code under src/node/; retarget the ./ and ./dashboard exports
- update json-render/dashboard alias, tsconfig.base paths, and the next-runtime-snapshot
  knip postcss config

The framework HOST examples (hub-*, a11y-messages-playground, demo-dock-client) mount
devframes rather than defining one, so they keep their framework-idiomatic layouts.

Author: antfubot

alias.ts

@@ -77,7 +77,7 @@ export const alias = {
   '@devframes/json-render-ui/hub': r('json-render-ui/src/hub.ts'),
   '@devframes/json-render-ui/spa': r('json-render-ui/src/spa.ts'),
   '@devframes/json-render-ui': r('json-render-ui/src/index.ts'),
-  'json-render/dashboard': fileURLToPath(new URL('./examples/json-render/src/dashboard.ts', import.meta.url)),
+  'json-render/dashboard': fileURLToPath(new URL('./examples/json-render/src/node/dashboard.ts', import.meta.url)),
   '@devframes/plugin-code-server/node': p('code-server/src/node/setup.ts'),
   '@devframes/plugin-code-server/constants': p('code-server/src/node/constants.ts'),
   '@devframes/plugin-code-server/types': p('code-server/src/node/types.ts'),

…mples/files-inspector/src/client/app.tsx examples/files-inspector/app/app.tsxexamples/files-inspector/src/client/app.tsx renamed to examples/files-inspector/app/app.tsx examples/files-inspector/src/client/app.tsx renamed to examples/files-inspector/app/app.tsx

@@ -1,3 +1,3 @@
 // Re-exports the shared devframe class-helper builders (see
 // `design/design.ts`) so this surface stays in lockstep with every other.
-export * from '../../../../design/design'
+export * from '../../../design/design'

…ples/streaming-chat/src/client/design.ts examples/files-inspector/app/design.tsexamples/streaming-chat/src/client/design.ts renamed to examples/files-inspector/app/design.ts examples/streaming-chat/src/client/design.ts renamed to examples/files-inspector/app/design.ts

@@ -0,0 +1,50 @@
+import type { Server } from 'node:http'
+import type { Plugin } from 'vite'
+import { fileURLToPath } from 'node:url'
+import preact from '@preact/preset-vite'
+import { initDevframe } from 'devframe/initiate'
+import { resolveBasePath } from 'devframe/internal'
+import UnoCSS from 'unocss/vite'
+import { defineConfig } from 'vite'
+import { alias } from '../../../alias'
+import devframe from '../src/node/index.ts'
+
+/**
+ * Serve-only plugin that bridges the node side (RPC + WebSocket +
+ * `__connection.json`) onto Vite's dev server under the devframe base path,
+ * mounted as a post middleware so Vite serves the HMR SPA first and the
+ * devframe host only answers the routes it owns. Inert during `vite build`.
+ */
+function filesInspectorDevBridge(): Plugin {
+  return {
+    name: 'files-inspector-dev-bridge',
+    apply: 'serve',
+    configureServer(server) {
+      const instance = initDevframe(devframe, {
+        base: resolveBasePath(devframe, 'hosted'),
+        distDir: false,
+        server: server.httpServer as Server,
+        auth: false,
+      })
+      return () => server.middlewares.use(instance.nodeMiddleware)
+    },
+  }
+}
+
+/**
+ * `base: './'` for the build keeps the mount path portable: the same output
+ * works whether devframe serves it at `/` (standalone) or under a base path
+ * (mounted in a hub). In `vite dev` the panel is served under the devframe
+ * base path so its `document.baseURI` matches production, and the dev bridge
+ * bridges the node side there with HMR.
+ */
+export default defineConfig(({ command }) => ({
+  base: command === 'serve' ? resolveBasePath(devframe, 'hosted') : './',
+  root: fileURLToPath(new URL('.', import.meta.url)),
+  resolve: { alias },
+  plugins: [UnoCSS(), preact(), filesInspectorDevBridge()],
+  build: {
+    outDir: fileURLToPath(new URL('../dist/client', import.meta.url)),
+    emptyOutDir: true,
+  },
+}))

…es/files-inspector/src/client/index.html examples/files-inspector/app/index.htmlexamples/files-inspector/src/client/index.html renamed to examples/files-inspector/app/index.html examples/files-inspector/src/client/index.html renamed to examples/files-inspector/app/index.html

@@ -1,7 +1,7 @@
 #!/usr/bin/env node
 import process from 'node:process'
 import { createCac } from 'devframe/adapters/cac'
-import devframe from './src/devframe.ts'
+import devframe from './src/node/index.ts'
 
 async function main() {
   // Serve the agent surface at `/__mcp` and register for `devframe connect`