refactor: unify into single muyue binary with embedded desktop mode

- Merge muyue + muyue-desktop into one binary (13MB)
- `muyue` starts TUI, `muyue desktop` launches web UI in browser
- Move frontend from cmd/muyue-desktop/frontend/ to web/ (standard Go layout)
- Add web/embed.go with //go:embed all:dist for frontend assets
- Add internal/desktop/ package (server, browser open, SPA routing, signals)
- Split internal/api/api.go into server.go + handlers.go
- Add internal/desktop/desktop.go with SPA fallback and --port/--no-open flags
- Clean package.json: remove unused @xterm/xterm, switch to ESM
- Fix vite.config.js proxy to use port 8095 for dev mode
- Add Makefile targets: frontend, desktop, dev-desktop
- Update all CI workflows: single binary build, web/ paths
- Remove cmd/muyue-desktop/ entirely

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

web/src/components/Studio.jsx

@@ -0,0 +1,126 @@
+import { useState, useRef, useEffect } from 'react'
+
+export default function Studio({ api }) {
+  const [messages, setMessages] = useState([
+    { role: 'ai', content: '>> Welcome to Studio! Chat with your AI assistant here.' },
+    { role: 'ai', content: '>> Configure agents and workflows from the sidebar.' },
+  ])
+  const [input, setInput] = useState('')
+  const [sidebarPanel, setSidebarPanel] = useState('chat')
+  const [loading, setLoading] = useState(false)
+  const messagesEnd = useRef(null)
+
+  useEffect(() => {
+    messagesEnd.current?.scrollIntoView({ behavior: 'smooth' })
+  }, [messages])
+
+  const handleSend = () => {
+    if (!input.trim() || loading) return
+    const text = input.trim()
+    setMessages(prev => [...prev, { role: 'user', content: '>> ' + text }])
+    setInput('')
+    setLoading(true)
+
+    api.runCommand(`echo "AI response simulation for: ${text}"`, '')
+      .then(res => {
+        setMessages(prev => [...prev, { role: 'ai', content: '>> ' + (res.output || res.error || 'No response') }])
+      })
+      .catch(err => {
+        setMessages(prev => [...prev, { role: 'ai', content: '[ERROR] ' + err.message }])
+      })
+      .finally(() => setLoading(false))
+  }
+
+  const handleKeyDown = (e) => {
+    if (e.key === 'Enter' && !e.shiftKey) {
+      e.preventDefault()
+      handleSend()
+    }
+  }
+
+  return (
+    <div className="split-horizontal">
+      <div className="chat-container" style={{ flex: 1, borderRight: '1px solid var(--border-dim)' }}>
+        <div style={{ padding: '12px 16px', borderBottom: '1px solid var(--border-dim)' }}>
+          <div className="section-header" style={{ margin: 0 }}>
+            Chat
+            {loading && <span className="loading-spinner" style={{ marginLeft: 8 }}> thinking...</span>}
+          </div>
+        </div>
+
+        <div className="chat-messages">
+          {messages.map((msg, i) => (
+            <div key={i} className={`chat-message ${msg.role}`}>
+              {msg.content}
+            </div>
+          ))}
+          <div ref={messagesEnd} />
+        </div>
+
+        <div className="chat-input-container">
+          <input
+            className="chat-input"
+            value={input}
+            onChange={e => setInput(e.target.value)}
+            onKeyDown={handleKeyDown}
+            placeholder="Type a message... (/plan <goal> for workflows)"
+            disabled={loading}
+          />
+          <button className="primary" onClick={handleSend} disabled={loading || !input.trim()}>
+            Send
+          </button>
+        </div>
+      </div>
+
+      <div className="split-right">
+        <div className="sidebar-section">
+          <div className="section-header">Studio</div>
+          {['chat', 'agents', 'workflows'].map(panel => (
+            <div
+              key={panel}
+              className={`sidebar-item ${sidebarPanel === panel ? 'active' : ''}`}
+              onClick={() => setSidebarPanel(panel)}
+            >
+              [{panel === 'chat' ? '#' : panel === 'agents' ? '*' : '~'}] {panel.charAt(0).toUpperCase() + panel.slice(1)}
+            </div>
+          ))}
+        </div>
+
+        <div style={{ borderTop: '1px solid var(--border-dim)', paddingTop: 12 }}>
+          {sidebarPanel === 'chat' && (
+            <div>
+              <div style={{ color: 'var(--text-muted)', fontSize: 12, marginBottom: 8 }}>Commands</div>
+              <div style={{ color: 'var(--dim-red)', fontSize: 12, fontFamily: 'var(--font-mono)' }}>
+                /plan {'<goal>'}<br/>
+                /help
+              </div>
+            </div>
+          )}
+
+          {sidebarPanel === 'agents' && (
+            <div>
+              <div style={{ color: 'var(--text-muted)', fontSize: 12, marginBottom: 8 }}>Active Agents</div>
+              <div style={{ padding: '4px 0' }}>
+                <span style={{ color: 'var(--text-main)', fontWeight: 600 }}>Crush</span>
+                <span style={{ color: 'var(--text-muted)', marginLeft: 8, fontSize: 11 }}>[|| stopped]</span>
+              </div>
+              <div style={{ padding: '4px 0' }}>
+                <span style={{ color: 'var(--text-main)', fontWeight: 600 }}>Claude Code</span>
+                <span style={{ color: 'var(--text-muted)', marginLeft: 8, fontSize: 11 }}>[|| stopped]</span>
+              </div>
+            </div>
+          )}
+
+          {sidebarPanel === 'workflows' && (
+            <div>
+              <div style={{ color: 'var(--text-muted)', fontSize: 12 }}>No active workflow.</div>
+              <div style={{ color: 'var(--dim-red)', fontSize: 12, marginTop: 8 }}>
+                Use /plan {'<goal>'} in chat to start.
+              </div>
+            </div>
+          )}
+        </div>
+      </div>
+    </div>
+  )
+}