fix(library): expose Delete control for Daedalus-managed libraries in UI

The backend already allows admin delete of a workspace-scoped Library via
the shared delete_library_cascade (commit 142e967), and the confirm-delete
page carries the Daedalus caution. But the detail template was never updated
to match: the Delete button stayed hardcoded `disabled` for any library with
a workspace_id, and the banner said "Do not delete it manually." So the
working route was unreachable from the UI — admins still could not clear an
orphaned Library blocking workspace re-registration.

Make Delete an unconditional enabled link to library:library-delete (the
confirm page already warns), and rewrite the workspace banner to describe the
escape hatch (deleting here removes embedded content; Daedalus recreates and
re-embeds on the next sync) instead of forbidding it.

Template-only change; no view/model/migration changes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

mnemosyne/library/templates/library/library_detail.html

@@ -25,14 +25,7 @@
     </div>
     <div class="flex gap-2">
         <a href="{% url 'library:library-edit' uid=library.uid %}" class="btn btn-sm btn-outline">Edit</a>
-        {% if library.workspace_id %}
-        <button type="button" class="btn btn-sm btn-error btn-outline" disabled
-                title="This library is managed by Daedalus. Delete it from the Daedalus workspace, not here.">
-            Delete
-        </button>
-        {% else %}
         <a href="{% url 'library:library-delete' uid=library.uid %}" class="btn btn-sm btn-error btn-outline">Delete</a>
-        {% endif %}
     </div>
 </div>
 
@@ -43,8 +36,11 @@
         <div class="text-sm opacity-80">
             This library was created for Daedalus workspace
             <code class="font-mono">{{ library.workspace_id }}</code>.
-            Items here are owned by the workspace; deleting the workspace in
-            Daedalus will remove this library. Do not delete it manually.
+            Normally you manage it from Daedalus. Deleting it here removes its
+            embedded content from Mnemosyne, but the source files still live in
+            Daedalus — it will be recreated and re-embedded on the next sync.
+            Use Delete to clear an orphaned library that is blocking workspace
+            re-registration.
         </div>
     </div>
 </div>