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

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

web/src/components/Shell.jsx

@@ -0,0 +1,150 @@
+import { useState, useRef, useEffect } from 'react'
+
+export default function Shell({ api }) {
+  const [history, setHistory] = useState([])
+  const [input, setInput] = useState('')
+  const [cwd, setCwd] = useState('~')
+  const [aiPanel, setAiPanel] = useState(true)
+  const [aiMessages, setAiMessages] = useState([
+    { role: 'ai', content: '>> I know your system inside out. Ask me anything.' }
+  ])
+  const [aiInput, setAiInput] = useState('')
+  const [aiLoading, setAiLoading] = useState(false)
+  const outputRef = useRef(null)
+
+  useEffect(() => {
+    outputRef.current?.scrollTo(0, outputRef.current.scrollHeight)
+  }, [history])
+
+  const handleCommand = async (cmd) => {
+    if (!cmd.trim()) return
+    if (cmd === 'clear') {
+      setHistory([])
+      return
+    }
+    if (cmd === 'exit' || cmd === 'quit') return
+
+    setHistory(prev => [...prev, { type: 'input', text: `${cwd} $ ${cmd}` }])
+
+    try {
+      const res = await api.runCommand(cmd, cwd === '~' ? '' : cwd)
+      if (res.output) {
+        setHistory(prev => [...prev, { type: 'output', text: res.output }])
+      }
+      if (res.error) {
+        setHistory(prev => [...prev, { type: 'error', text: res.error }])
+      }
+      if (cmd.startsWith('cd ')) {
+        const dir = cmd.slice(3).trim()
+        setCwd(dir === '~' ? '~' : dir)
+      }
+    } catch (err) {
+      setHistory(prev => [...prev, { type: 'error', text: err.message }])
+    }
+  }
+
+  const handleKeyDown = (e) => {
+    if (e.key === 'Enter') {
+      e.preventDefault()
+      handleCommand(input)
+      setInput('')
+    }
+  }
+
+  const handleAiSend = async () => {
+    if (!aiInput.trim() || aiLoading) return
+    const text = aiInput.trim()
+    setAiMessages(prev => [...prev, { role: 'user', content: '>> ' + text }])
+    setAiInput('')
+    setAiLoading(true)
+
+    try {
+      const res = await api.runCommand(`echo "AI: ${text}"`, '')
+      setAiMessages(prev => [...prev, { role: 'ai', content: '>> ' + (res.output || 'No response') }])
+    } catch (err) {
+      setAiMessages(prev => [...prev, { role: 'ai', content: '[ERROR] ' + err.message }])
+    }
+    setAiLoading(false)
+  }
+
+  return (
+    <div className="split-horizontal" style={{ height: '100%' }}>
+      <div className="terminal-container" style={{ flex: 1 }}>
+        <div style={{ padding: '8px 12px', borderBottom: '1px solid var(--border-dim)' }}>
+          <div className="section-header" style={{ margin: 0 }}>
+            Terminal
+            <span style={{ color: 'var(--dim-red)', fontWeight: 400, marginLeft: 12, fontSize: 11 }}>{cwd}</span>
+          </div>
+        </div>
+
+        <div className="terminal-output" ref={outputRef}>
+          {history.map((line, i) => (
+            <div key={i} style={{
+              color: line.type === 'input' ? 'var(--dim-red)' :
+                     line.type === 'error' ? 'var(--error)' : 'var(--text-main)',
+              whiteSpace: 'pre-wrap',
+              fontFamily: 'var(--font-mono)',
+              fontSize: 13,
+              lineHeight: 1.4,
+            }}>
+              {line.text}
+            </div>
+          ))}
+        </div>
+
+        <div className="terminal-input-row">
+          <span className="terminal-prompt">{'>'}</span>
+          <input
+            className="terminal-input"
+            value={input}
+            onChange={e => setInput(e.target.value)}
+            onKeyDown={handleKeyDown}
+            autoFocus
+          />
+        </div>
+      </div>
+
+      {aiPanel && (
+        <div style={{
+          width: 320,
+          borderLeft: '1px solid var(--border-dim)',
+          background: 'var(--bg-surface)',
+          display: 'flex',
+          flexDirection: 'column',
+        }}>
+          <div style={{ padding: '8px 12px', borderBottom: '1px solid var(--border-dim)' }}>
+            <div className="section-header" style={{ margin: 0 }}>AI Assistant</div>
+          </div>
+
+          <div style={{ flex: 1, overflow: 'auto', padding: 12 }}>
+            {aiMessages.map((msg, i) => (
+              <div key={i} style={{
+                marginBottom: 8,
+                padding: '6px 8px',
+                borderRadius: 'var(--radius)',
+                background: msg.role === 'ai' ? 'var(--bg-card)' : 'var(--muted-red)',
+                borderLeft: `3px solid ${msg.role === 'ai' ? 'var(--cyber-red)' : 'var(--cyber-rose)'}`,
+                fontSize: 12,
+                lineHeight: 1.4,
+              }}>
+                {msg.content}
+              </div>
+            ))}
+            {aiLoading && <span className="loading-spinner"> thinking...</span>}
+          </div>
+
+          <div style={{ padding: '8px 12px', borderTop: '1px solid var(--border-dim)', display: 'flex', gap: 6 }}>
+            <input
+              style={{ flex: 1, padding: '4px 8px', fontSize: 12 }}
+              value={aiInput}
+              onChange={e => setAiInput(e.target.value)}
+              onKeyDown={e => e.key === 'Enter' && handleAiSend()}
+              placeholder="Ask AI..."
+            />
+            <button style={{ padding: '4px 8px' }} onClick={handleAiSend}>Send</button>
+          </div>
+        </div>
+      )}
+    </div>
+  )
+}