fix: browser test fixes for flaky selectors and missing setup

- SidebarTab: Use placeholder selector instead of test ID for search input
- KeyboardHelper: Remove redundant canvas fallback (null is valid)
- groupNode: Use variable for category name instead of hardcoded string
- nodeLibrary: Ensure tab is open before filling search input
- subgraph: Reload workflow after page reload to restore state
- useSettingSearch: Use role selector and simplify selected class assertion

Amp-Thread-ID: https://ampcode.com/threads/T-019c18c2-667a-7179-bb2d-86f35cd1d7b0
Co-authored-by: Amp <amp@ampcode.com>

browser_tests/fixtures/helpers/KeyboardHelper.ts

@@ -20,26 +20,26 @@ export class KeyboardHelper {
   }
 
   async selectAll(locator?: Locator | null): Promise<void> {
-    await this.ctrlSend('KeyA', locator ?? this.canvas)
+    await this.ctrlSend('KeyA', locator)
   }
 
   async bypass(locator?: Locator | null): Promise<void> {
-    await this.ctrlSend('KeyB', locator ?? this.canvas)
+    await this.ctrlSend('KeyB', locator)
   }
 
   async undo(locator?: Locator | null): Promise<void> {
-    await this.ctrlSend('KeyZ', locator ?? this.canvas)
+    await this.ctrlSend('KeyZ', locator)
   }
 
   async redo(locator?: Locator | null): Promise<void> {
-    await this.ctrlSend('KeyY', locator ?? this.canvas)
+    await this.ctrlSend('KeyY', locator)
   }
 
   async moveUp(locator?: Locator | null): Promise<void> {
-    await this.ctrlSend('ArrowUp', locator ?? this.canvas)
+    await this.ctrlSend('ArrowUp', locator)
   }
 
   async moveDown(locator?: Locator | null): Promise<void> {
-    await this.ctrlSend('ArrowDown', locator ?? this.canvas)
+    await this.ctrlSend('ArrowDown', locator)
   }
 }