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>

tools/ci-tools.ts

@@ -83,7 +83,7 @@ async function setPrLabels(): Promise<void> {
         Accept: 'application/vnd.github+json',
         Authorization: `Bearer ${env.GITHUB_TOKEN}`,
         'X-GitHub-Api-Version': '2022-11-28',
-        ...(body ? {'Content-Type': 'application/json'} : {}),
+        ...(Boolean(body) && {'Content-Type': 'application/json'}),
       },
       body: body ? JSON.stringify(body) : undefined,
     });