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/api/client.js

@@ -0,0 +1,31 @@
+const API_BASE = '/api'
+
+async function request(path, options = {}) {
+  const res = await fetch(`${API_BASE}${path}`, {
+    headers: { 'Content-Type': 'application/json' },
+    ...options,
+  })
+  if (!res.ok) {
+    const err = await res.json().catch(() => ({ error: res.statusText }))
+    throw new Error(err.error || res.statusText)
+  }
+  return res.json()
+}
+
+const api = {
+  getInfo: () => request('/info'),
+  getSystem: () => request('/system'),
+  getTools: () => request('/tools'),
+  getConfig: () => request('/config'),
+  getProviders: () => request('/providers'),
+  getSkills: () => request('/skills'),
+  getLSP: () => request('/lsp'),
+  getMCP: () => request('/mcp'),
+  getUpdates: () => request('/updates'),
+  runScan: () => request('/scan', { method: 'POST' }),
+  installTools: (tools) => request('/install', { method: 'POST', body: JSON.stringify({ tools }) }),
+  configureMCP: () => request('/mcp/configure', { method: 'POST' }),
+  runCommand: (command, cwd) => request('/terminal', { method: 'POST', body: JSON.stringify({ command, cwd }) }),
+}
+
+export default api