fix(ui): remove Tests tab, remove raw-md/collapse toggles, add Copy MD button, bump v0.9.1

- Remove Tests tab from navigation (browsertest still works via snippet/extension)
- Remove showRawMarkdown and collapseHistory toggles from Studio input bar
- Add "Copy MD" button on each assistant message header to copy raw markdown
- Bump version to 0.9.1

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

web/src/components/App.jsx

@@ -1,5 +1,5 @@
 import { useState, useEffect, useCallback, useMemo, useRef } from 'react'
-import { LayoutDashboard, Sparkles, Terminal, Settings, TestTube2 } from 'lucide-react'
+import { LayoutDashboard, Sparkles, Terminal, Settings } from 'lucide-react'
 import api from '../api/client'
 import { getTheme, applyTheme } from '../themes'
 import { useI18n } from '../i18n'
@@ -7,7 +7,6 @@ import Dashboard from './Dashboard'
 import Studio from './Studio'
 import Shell from './Shell'
 import Config from './Config'
-import Tests from './Tests'
 import OnboardingWizard from './OnboardingWizard'
 
 export default function App() {
@@ -25,7 +24,6 @@ export default function App() {
     { id: 'dash', label: t('tabs.dashboard'), icon: <LayoutDashboard size={15} /> },
     { id: 'studio', label: t('tabs.studio'), icon: <Sparkles size={15} /> },
     { id: 'shell', label: t('tabs.shell'), icon: <Terminal size={15} /> },
-    { id: 'tests', label: 'Tests', icon: <TestTube2 size={15} /> },
     { id: 'config', label: t('tabs.config'), icon: <Settings size={15} /> },
   ], [t])
 
@@ -56,8 +54,7 @@ export default function App() {
         Digit1: 'dash',
         Digit2: 'studio',
         Digit3: 'shell',
-        Digit4: 'tests',
-        Digit5: 'config',
+        Digit4: 'config',
       }
       if (map[e.code]) {
         e.preventDefault()
@@ -134,7 +131,6 @@ export default function App() {
         <div className={activeTab === 'dash' ? '' : 'tab-hidden'}><Dashboard api={api} refreshRef={dashRefreshRef} /></div>
         <div className={activeTab === 'studio' ? '' : 'tab-hidden'}><Studio api={api} /></div>
         <div className={activeTab === 'shell' ? '' : 'tab-hidden'}><Shell api={api} isSudo={isSudo} /></div>
-        <div className={activeTab === 'tests' ? '' : 'tab-hidden'}><Tests api={api} /></div>
         <div className={activeTab === 'config' ? '' : 'tab-hidden'}><Config api={api} /></div>
       </main>