Replace hotwire with htmx

In the process, also improve the feedback from the import/add feed
forms.

I also replaced the frontend code to replace utc timestamps with local
time strings with @hotwired/stimulus with vanilla js.

frontend/js/localTimeController.ts

@@ -0,0 +1,24 @@
+function convertTimeElements() {
+  const timeElements = document.querySelectorAll('time.local-time');
+  timeElements.forEach((element) => {
+    const utcString = element.getAttribute("datetime");
+    if (utcString) {
+      const utcTime = new Date(utcString);
+      element.textContent = utcTime.toLocaleDateString(window.navigator.language, {
+        year: "numeric",
+        month: "long",
+        day: "numeric",
+      });
+    } else {
+      console.error("Missing datetime attribute on time.local-time element", element);
+    }
+  });
+}
+
+document.addEventListener("DOMContentLoaded", function() {
+  convertTimeElements();
+});
+
+document.body.addEventListener('htmx:afterSwap', function() {
+  convertTimeElements();
+});