Add role=search on container; mark list as role=list; harden clearConversations empty state

- Use role=search for the search container for better semantics
- Mark chat list as role=list while retaining native button items for activation
- Make Clear conversations resilient to empty list after reset
Build and lint pass.

Author: PeterDaveHello

src/pages/IndependentPanel/App.jsx

@@ -106,9 +106,14 @@ function App() {
   }
 
   const clearConversations = async () => {
-    const sessions = await resetSessions()
-    setSessions(sessions)
-    await setSessionIdSafe(sessions[0].sessionId)
+    const next = await resetSessions()
+    setSessions(next)
+    if (next && next.length > 0) {
+      await setSessionIdSafe(next[0].sessionId)
+    } else {
+      setSessionId(null)
+      setCurrentSession(null)
+    }
   }
 
   const handleSearchChange = (e) => {
@@ -217,7 +222,7 @@ function App() {
               {t('Export')}
             </button>
           </div>
-          <div className="search-container">
+          <div className="search-container" role="search">
             <input
               type="search"
               placeholder={t('Search conversations...')}
@@ -234,7 +239,7 @@ function App() {
             />
           </div>
           <hr />
-          <div className="chat-list" id="chat-list">
+          <div className="chat-list" id="chat-list" role="list">
             {filteredSessions.length === 0 && (
               <div className="no-results" role="status" aria-live="polite">
                 {t('No conversations found')}