Navbar returns a Safe node; drop redundant filter_presets mark_safe

Navbar is static chrome (a few reverse() URLs in otherwise-fixed markup), so
it now returns a single Safe node wrapping that markup instead of a mark_safe
string — consistent with "trusted HTML is a Safe node," and a full element
tree would be ~80 lines of nesting for no gain (it owns no component JS).
Page() interpolates it via str() exactly as before.

filter_presets.list_presets returned HttpResponse(mark_safe(...)); HttpResponse
never escapes its body, so the mark_safe was pure noise — dropped.

The mark_safe calls that remain are all load-bearing and not tree children:
the node engine itself (core: how a node emits its SafeString), the
script-tag / scripts= string helpers, and Page()'s final document string.

Full suite green (445).

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

games/views/filter_presets.py

@@ -8,7 +8,6 @@ from django.contrib.auth.decorators import login_required
 from django.http import HttpRequest, HttpResponse
 from django.shortcuts import get_object_or_404, redirect
 from django.urls import reverse
-from django.utils.safestring import mark_safe
 
 from games.models import FilterPreset
 
@@ -40,7 +39,7 @@ def list_presets(request: HttpRequest) -> HttpResponse:
     if not items:
         items = ['<li class="px-4 py-2 text-sm text-body italic">No saved presets</li>']
 
-    return HttpResponse(mark_safe(f'<ul class="py-1">{"".join(items)}</ul>'))
+    return HttpResponse(f'<ul class="py-1">{"".join(items)}</ul>')
 
 
 @login_required