Also bundle css with bun so it busts caches

And updates the `build.rs` script so that it also builds a manifest.txt
for css files.

frontend/js/index.ts

@@ -0,0 +1,9 @@
+import { Application } from "@hotwired/stimulus";
+
+import LocalTimeController from "./local_time_controller";
+
+// import CSS so it gets named with a content hash that busts caches
+import "../css/styles.css";
+
+window.Stimulus = Application.start();
+window.Stimulus.register("local-time", LocalTimeController);

frontend/js/local_time_controller.ts

@@ -0,0 +1,28 @@
+import { Controller } from "@hotwired/stimulus";
+
+// Replaces all UTC timestamps with time formated for the local timezone
+export default class extends Controller {
+  connect() {
+    this.renderLocalTime();
+  }
+
+  renderLocalTime() {
+    this.element.textContent = this.localTimeString;
+  }
+
+  get localTimeString(): string {
+    if (this.utcTime) {
+      return this.utcTime.toLocaleDateString(window.navigator.language, {
+        year: "numeric",
+        month: "long",
+        day: "numeric",
+      });
+    }
+    return "Unknown datetime"
+  }
+
+  get utcTime(): Date | null {
+    const utcString = this.element.getAttribute("datetime");
+    return utcString ? new Date(utcString) : null;
+  }
+}