refactor: remove locale panel, improve provider validation and terminal buffer persistence

- Remove locale panel from config (language/keyboard already handled elsewhere)
- Add per-provider key validation status with auto-check on load
- Add missing tools section with AI-powered installation
- Improve reset confirmation with modal
- Persist terminal buffer to localStorage with auto-save
- Detect clear command to wipe saved buffer
- Remove AI tab concept (commands routed to active tab instead)
- Remove renderTick hacks, use proper message keys

💘 Generated with Crush

Assisted-by: MiniMax-M2.7 via Crush <crush@charm.land>

web/src/components/Studio.jsx

@@ -309,7 +309,6 @@ export default function Studio({ api }) {
   const [tokenInfo, setTokenInfo] = useState({ used: 0, max: 100000, summarizeAt: 80000 })
   const [contextCollapsed, setContextCollapsed] = useState(false)
   const [messagesCollapsed, setMessagesCollapsed] = useState(false)
-  const [renderTick, setRenderTick] = useState(0)
   const messagesEnd = useRef(null)
   const feedRef = useRef(null)
   const textareaRef = useRef(null)
@@ -342,12 +341,6 @@ export default function Studio({ api }) {
     messagesEnd.current?.scrollIntoView({ behavior: 'smooth' })
   }, [messages, streaming, streamThinking, streamToolCalls])
 
-  useEffect(() => {
-    const ms = loading ? 1000 : 5000
-    const iv = setInterval(() => setRenderTick(t => t + 1), ms)
-    return () => clearInterval(iv)
-  }, [loading])
-
   useEffect(() => {
     const onTab = (e) => {
       if (e.key !== 'Tab') return
@@ -648,7 +641,7 @@ export default function Studio({ api }) {
       return (
         <>
           {messages.slice(0, visibleCount).map(msg => (
-            <FeedItem key={`${msg.id}-${renderTick}`} msg={msg} />
+            <FeedItem key={msg.id} msg={msg} />
           ))}
           <div className="feed-collapsed-messages" onClick={handleToggleCollapsed}>
             <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
@@ -661,7 +654,7 @@ export default function Studio({ api }) {
       )
     }
     return messages.map(msg => (
-      <FeedItem key={`${msg.id}-${renderTick}`} msg={msg} />
+      <FeedItem key={msg.id} msg={msg} />
     ))
   }