Restore sidebar view when clicking back (#28167)

Author: piitaya

src/panels/lovelace/views/hui-sections-view.ts

@@ -123,6 +123,7 @@ export class SectionsView extends LitElement implements LovelaceViewElement {
       "section-visibility-changed",
       this._sectionVisibilityChanged
     );
+    this._showSidebar = Boolean(window.history.state?.sidebar);
   }
 
   disconnectedCallback(): void {
@@ -428,6 +429,12 @@ export class SectionsView extends LitElement implements LovelaceViewElement {
 
     this._showSidebar = !this._showSidebar;
 
+    // Add sidebar state to history
+    window.history.replaceState(
+      { ...window.history.state, sidebar: this._showSidebar },
+      ""
+    );
+
     // Restore scroll position after view updates
     this.updateComplete.then(() => {
       const scrollY = this._showSidebar