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.

src/partials/layout.rs

@@ -95,9 +95,8 @@ impl Layout {
                     meta charset="utf-8";
                     title { (self.title) }
                     // TODO: vendor this before going to prod
-                    script type="module" {
-                        r#"import * as Turbo from 'https://cdn.skypack.dev/@hotwired/turbo';"#
-                    }
+                    script src="https://unpkg.com/htmx.org@1.9.5" integrity="sha384-xcuj3WpfgjlKF+FXhSQFQ0ZNr39ln+hwjN3npfM9VBnUskLolQAcN80McRIVOPuO" crossorigin="anonymous" {}
+                    script src="https://unpkg.com/htmx.org/dist/ext/sse.js" {}
                     @for js_bundle in js_bundles() {
                         script type="module" src=(js_bundle) {}
                     }
@@ -105,7 +104,7 @@ impl Layout {
                         link rel="stylesheet" href=(css_bundle) {}
                     }
                 }
-                body {
+                body hx-booster="true" {
                     (header(&self.title))
                     (template)
                 }