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/features/heatmap.ts

@@ -24,8 +24,8 @@ export async function initHeatmap() {
       heatmap[dateStr] = (heatmap[dateStr] || 0) + contributions;
     }
 
-    const values = Object.keys(heatmap).map((v) => {
-      return {date: new Date(v), count: heatmap[v]};
+    const values = Object.entries(heatmap).map(([dateStr, count]) => {
+      return {date: new Date(dateStr), count};
     });
 
     const totalFormatted = totalContributions.toLocaleString();