chore: upgrade eslint plugins, remove eslint-plugin-github (#38046)

- Bump `eslint`, `typescript-eslint` and `eslint-plugin-unicorn` (to
v68), and configure the rules added in unicorn v66/v67/v68.
- Remove `eslint-plugin-github` and its workarounds (rules, type stub,
pnpm peer override, in-code `eslint-disable` comments); the rules worth
keeping are covered by `unicorn` equivalents.
- Apply the resulting fixes and autofixes across the JS codebase.

_Prepared with Claude (Opus 4.8)._

---------

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

web_src/js/markup/render-iframe.test.ts

@@ -29,7 +29,6 @@ describe('navigateToIframeLink', () => {
 
   test('unsafe links', () => {
     const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => undefined);
-    window.location.href = 'http://localhost:3000/';
 
     // eslint-disable-next-line no-script-url
     navigateToIframeLink('javascript:void(0);', '_blank');