Fix remaining typescript issues, enable tsc (#32840)

Fixes 79 typescript errors. Discovered at least two bugs in
`notifications.ts`, and I'm pretty sure this feature was at least
partially broken and may still be, I don't really know how to test it.

After this, only like ~10 typescript errors remain in the codebase but
those are harder to solve.

---------

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

web_src/js/features/comp/ReactionSelector.ts

@@ -3,7 +3,7 @@ import {fomanticQuery} from '../../modules/fomantic/base.ts';
 
 export function initCompReactionSelector(parent: ParentNode = document) {
   for (const container of parent.querySelectorAll('.issue-content, .diff-file-body')) {
-    container.addEventListener('click', async (e) => {
+    container.addEventListener('click', async (e: MouseEvent & {target: HTMLElement}) => {
       // there are 2 places for the "reaction" buttons, one is the top-right reaction menu, one is the bottom of the comment
       const target = e.target.closest('.comment-reaction-button');
       if (!target) return;