Add new text button and expand sidebar functionality in App.tsx

src/App.tsx

@@ -1442,6 +1442,7 @@ export default function App() {
       <main className="workspace">
         <div className="workspace__body">
           {!selectedTextId ? (
+            <>
               <div className="empty-state">
                 <div className="empty-state__title">Create your first text</div>
                 <div className="empty-state__subtitle">
@@ -1451,6 +1452,20 @@ export default function App() {
                   New Text
                 </button>
               </div>
+              {sidebarCollapsed ? (
+                <div className="editor__footer">
+                  <button
+                    className="icon-button"
+                    onClick={() => setSidebarCollapsed(false)}
+                    aria-label="Expand sidebar"
+                    title="Expand sidebar"
+                    type="button"
+                  >
+                    <span className="icon-button__glyph" aria-hidden="true">▶</span>
+                  </button>
+                </div>
+              ) : null}
+            </>
           ) : (
             <div
               className={`workspace__content${