templates: update script tags for ES modules and reader link

- Change script tags from 'defer' to 'type=module' for ES module support
- Add reader.js script to reader.templ for the reader bundle
- Update book_detail.templ 'Read Now' button to link to /readers/{id}
- Remove trailing blank line from register.templ

templates/book_detail.templ

@@ -52,7 +52,7 @@ templ BookDetail(user User, book handlers.MediaDetail, errorMessage string) {
 						<div class="flex flex-wrap gap-3 mb-6">
 							<!-- Read Now (placeholder) -->
 							<button
-								@click="showReaderPlaceholder()"
+								@click={ "window.location.href = '/readers/" + uuidToString(book.ID) + "'" }
 								class="px-6 py-3 rounded-lg font-semibold"
 								style="background-color: var(--accent); color: white;"
 							>