Vastly overhaul admin UI

Admin UI now has the ability to edit links that exist. Deleting items is
more accessible and asks for a confirmation before deleting. Link and
Category names as well as link descriptions now have a length limit
(todo: make it configurable?). Small bug fixes related to image saving
are also included in this commit.

src/templates/partials/modals/delete-category.hbs

@@ -0,0 +1,13 @@
+<div id="category-delete-contents" class="hidden text-center">
+    <h3>Are you sure you want to delete this category?</h3>
+    <p class="mb-3">You are about to delete the category <strong id="category-name"></strong>. This action cannot be
+        undone.
+        All links associated with this category will also be deleted. Are you sure you want to continue?</p>
+    <div class="flex justify-end flex-col gap-y-2">
+        <button class="px-4 py-2 rounded-md w-full bg-error text-white border-0"
+            onclick="confirmDeleteCategory()">Delete
+            category</button>
+        <button class="px-4 py-2 rounded-md w-full bg-overlay border border-highlight text-white"
+            onclick="closeModal()">Cancel</button>
+    </div>
+</div>