Add e2e reaction test, improve accessibility, enable parallel testing (#37081)

Add a new e2e test for toggling issue reactions via the reaction picker
dropdown.

Add `aria-label` attributes to improve reaction accessibility:
- Add `aria-label="Reaction"` to the reaction picker dropdown
- Add `role="group"` with `aria-label="Reactions"` to the reactions
container, giving it a semantic identity for screen readers
- Include the reaction key in each reaction button's `aria-label` (e.g.
`+1: user1, user2`) so screen readers announce which reaction a button
represents

E2e test improvements:
- Simplify `randomString` to use `Math.random` instead of `node:crypto`
- Replace `generatePassword` with a static password, remove unused
`clickDropdownItem`
- Enable `fullyParallel: true` and `workers: '50%'` in Playwright config
- Run both chromium and firefox in all environments (not just CI)
- Parallelize `login` and `apiCreateRepo` setup where possible
- Use dedicated test user in `user-settings` test for concurrency safety

Co-authored-by: Claude (Opus 4.6) <noreply@anthropic.com>

tests/e2e/utils.ts

@@ -1,7 +1,16 @@
-import {randomBytes} from 'node:crypto';
 import {env} from 'node:process';
 import {expect} from '@playwright/test';
-import type {APIRequestContext, Locator, Page} from '@playwright/test';
+import type {APIRequestContext, Page} from '@playwright/test';
+
+/** Generate a random alphanumeric string. */
+export function randomString(length: number): string {
+  const chars = 'abcdefghijklmnopqrstuvwxyz0123456789';
+  let result = '';
+  for (let index = 0; index < length; index++) {
+    result += chars.charAt(Math.floor(Math.random() * chars.length));
+  }
+  return result;
+}
 
 export const timeoutFactor = Number(env.GITEA_TEST_E2E_TIMEOUT_FACTOR) || 1;
 
@@ -63,14 +72,8 @@ export async function apiDeleteOrg(requestContext: APIRequestContext, name: stri
   }), 'apiDeleteOrg');
 }
 
-/** Generate a random password that satisfies the complexity requirements. */
-function generatePassword() {
-  const chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
-  return `${Array.from(randomBytes(12), (b) => chars[b % chars.length]).join('')}!aA1`;
-}
-
-/** Random password shared by all test users — used for both API user creation and browser login. */
-const testUserPassword = generatePassword();
+/** Password shared by all test users — used for both API user creation and browser login. */
+const testUserPassword = 'e2e-password!aA1';
 
 export function apiUserHeaders(username: string) {
   return apiAuthHeader(username, testUserPassword);
@@ -89,11 +92,6 @@ export async function apiDeleteUser(requestContext: APIRequestContext, username:
   }), 'apiDeleteUser');
 }
 
-export async function clickDropdownItem(page: Page, trigger: Locator, itemText: string) {
-  await trigger.click();
-  await page.getByText(itemText).click();
-}
-
 export async function loginUser(page: Page, username: string) {
   return login(page, username, testUserPassword);
 }