feat: use KaTeX to render math exprs

src/ts/app.ts

@@ -1,6 +1,18 @@
 declare const bootstrap: any;
+declare const katex: any;
 
 (() => {
     const list = document.querySelectorAll('[data-bs-toggle="tooltip"]');
     list.forEach((el: Element) => new bootstrap.Tooltip(el));
+
+    window.onload = function () {
+        const tex = document.getElementsByClassName("math");
+        Array.prototype.forEach.call(tex, function (el) {
+            let content = el.textContent.trim();
+            if (content.startsWith("\\[")) content = content.slice(2);
+            if (content.endsWith("\\]")) content = content.slice(0, -2);
+
+            katex.render(content, el);
+        });
+    };
 })();