chore: update eslint and stylelint configs and re-sync modern-normalize (#38982)

- update the vendored `modern-normalize` to v3.0.1
- require descriptions for lint disables in TS and CSS, same as we
already have in Go.
- disable core rules covered by `regexp/*` and `unicorn/*`, and ones
that cannot fire
- stop applying vitest rules to the playwright files in `tests/e2e`
- enable 7 stylelint rules, mostly `no-unknown` and `no-invalid` checks
- drop 2 unnecessary vendor prefixes (safari v17+, chrome v120+)
- look up ids via `querySelector` with `CSS.escape` instead of
`getElementById`
- remove stale doc about `@ts-expect-error`, it's forbidden
- misc dev doc fixes

Every declaration that `modern-normalize` v3 removes was checked against
chromium, webkit and firefox defaults first. The `hr` color and the
`:-moz-focusring` outline are kept as documented deviations, dropping
those does change rendering.

---------

Signed-off-by: silverwind <me@silverwind.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

tests/e2e/file-view-render.test.ts

@@ -3,7 +3,7 @@ import {expect, test} from '@playwright/test';
 import {apiCreateRepo, apiCreateFile, assertFlushWithParent, assertNoJsError, login, randomString} from './utils.ts';
 
 test('3d model file', async ({page, request, browserName}) => {
-  test.skip(browserName === 'firefox', 'unclear firefox-only CI-only failure'); // eslint-disable-line playwright/no-skipped-test
+  test.skip(browserName === 'firefox', 'unclear firefox-only CI-only failure'); // eslint-disable-line playwright/no-skipped-test -- conditional skip, the reason is in the message
   const repoName = `e2e-3d-render-${randomString(8)}`;
   const owner = env.GITEA_TEST_E2E_USER;
   await apiCreateRepo(request, {name: repoName});

tests/e2e/webauthn.test.ts

@@ -19,7 +19,7 @@ async function signInWithPassword(page: Page, username: string) {
 
 // regression: credProtect level 3 hid the credential from the second-factor login
 test('security key survives credProtect', async ({page, request, browserName}) => {
-  test.skip(browserName !== 'chromium', 'only the CDP authenticator emulates credProtect'); // eslint-disable-line playwright/no-skipped-test
+  test.skip(browserName !== 'chromium', 'only the CDP authenticator emulates credProtect'); // eslint-disable-line playwright/no-skipped-test -- conditional skip, the reason is in the message
 
   const username = `e2e-credprotect-${randomString(8)}`;
   await apiCreateUser(request, username);