feat: AI task API, token-based context windows, SSH password auth, sudo bypass detection

Replace message-count context windows with token-budget based ones for both
studio and shell. Add /api/ai/task endpoint for background tool
check/install/update. Enhance sudo blocking to catch piped/chained elevation
commands. Add SSH password support via sshpass and connection editing UI.
Remove realTokens persistence in favor of consumption tracking. Bump to 0.4.1.

💘 Generated with Crush

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

web/src/components/App.jsx

@@ -146,7 +146,7 @@ export default function App() {
       <main className="content">
         <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} /></div>
+        <div className={activeTab === 'shell' ? '' : 'tab-hidden'}><Shell api={api} isSudo={isSudo} /></div>
         <div className={activeTab === 'config' ? '' : 'tab-hidden'}><Config api={api} /></div>
       </main>