Install htmx via bun instead of unpkg CDN

frontend/js/index.ts

@@ -1,4 +1,15 @@
+import htmx from 'htmx.org';
+import 'htmx.org/dist/ext/sse';
+
 // import CSS so it gets named with a content hash that busts caches
 import '../css/styles.css';
 
 import './localTimeController';
+
+declare global {
+  interface Window {
+    htmx: typeof htmx;
+  }
+}
+
+window.htmx = htmx;