IndependentPanel: Replace nested button with div role=button

Avoid invalid nested <button> by using a focusable div with role=button.
Preserves styling and click/keyboard behavior while preventing event
bubbling issues and improving a11y in the chat list.

Author: PeterDaveHello

src/pages/IndependentPanel/App.jsx

@@ -232,14 +232,22 @@ function App() {
             {filteredSessions
               .filter((session) => Boolean(session.sessionId))
               .map((session) => (
-                <button
+                <div
                   key={session.sessionId}
+                  role="button"
+                  tabIndex={0}
                   className={`normal-button chat-list-item ${
                     sessionId === session.sessionId ? 'active' : ''
                   }`}
                   onClick={() => {
                     setSessionIdSafe(session.sessionId)
                   }}
+                  onKeyDown={(e) => {
+                    if (e.key === 'Enter' || e.key === ' ') {
+                      e.preventDefault()
+                      setSessionIdSafe(session.sessionId)
+                    }
+                  }}
                 >
                   {session.sessionName}
                   <span
@@ -280,7 +288,7 @@ function App() {
                       }}
                     />
                   </span>
-                </button>
+                </div>
               ))}
           </div>
           <hr />