Adds admin permissions management page

Implements an admin permissions management page.

This change allows superusers to manage permissions directly from the castle interface, providing a more streamlined experience for administrative tasks.

views.py

@@ -17,3 +17,17 @@ async def index(
     return template_renderer(["castle/templates"]).TemplateResponse(
         request, "castle/index.html", {"user": user.json()}
     )
+
+
+@castle_generic_router.get(
+    "/permissions",
+    description="Permission management page",
+    response_class=HTMLResponse,
+)
+async def permissions(
+    request: Request,
+    user: User = Depends(check_user_exists),
+):
+    return template_renderer(["castle/templates"]).TemplateResponse(
+        request, "castle/permissions.html", {"user": user.json()}
+    )