fix(e2e): fix admin tag test (use existing tag) and annotation locator

- Admin tag test: "Familie" never existed in the database; use "Fest"
  which is a real seeded tag, with a matching rename-back to restore state
- Annotation hash test: the broad `[data-testid^="annotation-"]` locator
  also matched `annotation-side-panel` (always in DOM, even when
  off-screen); extend the :not() exclusion list to cover it

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/e2e/documents.spec.ts

@@ -461,9 +461,11 @@ test.describe('PDF annotations — file hash versioning', () => {
 		await page.waitForSelector('[data-hydrated]');
 		await page.locator('canvas').first().waitFor({ state: 'visible', timeout: 20000 });
 
-		// Use :not() to exclude the outdated-notice element whose testid also starts with "annotation-"
+		// Use :not() to exclude the outdated-notice and side-panel elements whose testid also starts with "annotation-"
 		await expect(
-			page.locator('[data-testid^="annotation-"]:not([data-testid="annotation-outdated-notice"])')
+			page.locator(
+				'[data-testid^="annotation-"]:not([data-testid="annotation-outdated-notice"]):not([data-testid="annotation-side-panel"])'
+			)
 		).toHaveCount(0, { timeout: 8000 });
 		await expect(page.locator('[data-testid="annotation-outdated-notice"]')).toBeVisible({
 			timeout: 5000