feat: add interactive dev mode selector (pnpm dev)

Adds a zero-dependency Node.js script with arrow-key selection
for choosing between Desktop (Electron), Web (CLI serve + frontend),
Server Only (API backend), and Frontend-only dev modes.

Remembers last selection in node_modules/.cache/dev-mode.

package.json

@@ -20,6 +20,7 @@
     ]
   },
   "scripts": {
+    "dev": "node scripts/dev-select.mjs",
     "dev:desktop": "pnpm --filter @openchatlab/desktop dev",
     "build:desktop": "pnpm --filter @openchatlab/desktop build",
     "build:mac": "pnpm --filter @openchatlab/desktop build:mac",

scripts/dev-select.mjs

@@ -0,0 +1,92 @@
+#!/usr/bin/env node
+
+/**
+ * Interactive dev mode selector.
+ * Usage: node scripts/dev-select.mjs
+ *
+ * Arrow keys to move, Enter to confirm.
+ * Remembers last selection in node_modules/.cache/dev-mode.
+ */
+
+import { execSync } from 'child_process'
+import { readFileSync, writeFileSync, mkdirSync } from 'fs'
+import { join, dirname } from 'path'
+import { fileURLToPath } from 'url'
+
+const __dirname = dirname(fileURLToPath(import.meta.url))
+const rootDir = join(__dirname, '..')
+const cacheFile = join(rootDir, 'node_modules', '.cache', 'dev-mode')
+
+const options = [
+  { key: 'desktop', label: 'Desktop      (Electron)', command: 'pnpm run dev:desktop' },
+  { key: 'web', label: 'Web          (CLI serve + frontend)', command: 'pnpm run dev:web' },
+  { key: 'server', label: 'Server Only  (API backend)', command: 'pnpm run dev:serve' },
+  { key: 'frontend', label: 'Frontend     (no backend)', command: 'pnpm run dev:app' },
+]
+
+function loadLastChoice() {
+  try {
+    const key = readFileSync(cacheFile, 'utf8').trim()
+    const idx = options.findIndex((o) => o.key === key)
+    return idx >= 0 ? idx : 0
+  } catch {
+    return 0
+  }
+}
+
+function saveChoice(key) {
+  try {
+    mkdirSync(dirname(cacheFile), { recursive: true })
+    writeFileSync(cacheFile, key)
+  } catch {
+    // best-effort
+  }
+}
+
+let selected = loadLastChoice()
+
+function render() {
+  process.stdout.write(`\x1b[${options.length}A`)
+  for (let i = 0; i < options.length; i++) {
+    const prefix = i === selected ? '\x1b[36m❯\x1b[0m' : ' '
+    const text = i === selected ? `\x1b[1m${options[i].label}\x1b[0m` : options[i].label
+    process.stdout.write(`\x1b[2K  ${prefix} ${text}\n`)
+  }
+}
+
+function run() {
+  console.log('\n\x1b[1mSelect dev mode:\x1b[0m  (↑↓ to move, Enter to confirm)\n')
+  for (let i = 0; i < options.length; i++) process.stdout.write('\n')
+  render()
+
+  process.stdin.setRawMode(true)
+  process.stdin.resume()
+  process.stdin.setEncoding('utf8')
+
+  process.stdin.on('data', (key) => {
+    if (key === '\x1b[A') {
+      selected = (selected - 1 + options.length) % options.length
+      render()
+    } else if (key === '\x1b[B') {
+      selected = (selected + 1) % options.length
+      render()
+    } else if (key === '\r' || key === '\n') {
+      process.stdin.setRawMode(false)
+      process.stdin.pause()
+      const choice = options[selected]
+      saveChoice(choice.key)
+      console.log(`\n\x1b[32m▶\x1b[0m Running: ${choice.command}\n`)
+      try {
+        execSync(choice.command, { stdio: 'inherit' })
+      } catch {
+        process.exit(1)
+      }
+    } else if (key === '\x03') {
+      process.stdin.setRawMode(false)
+      console.log()
+      process.exit(0)
+    }
+  })
+}
+
+run()