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>

common/layout.py

@@ -186,10 +186,16 @@ def _main_script(mastered: bool) -> str:
     return _MAIN_SCRIPT_A + ("true" if mastered else "false") + _MAIN_SCRIPT_B
 
 
-def Navbar(*, today_played: str, last_7_played: str, current_year: int) -> SafeText:
-    """Top navigation bar."""
+def Navbar(*, today_played: str, last_7_played: str, current_year: int) -> "Node":
+    """Top navigation bar.
+
+    Static chrome, so it's a single ``Safe`` node wrapping its markup rather
+    than a hand-built element tree — trusted HTML belongs in a ``Safe`` node,
+    not a ``mark_safe`` string."""
+    from common.components import Safe
+
     logo = static("icons/schedule.png")
-    return mark_safe(f"""<nav class="bg-neutral-primary-soft border-b border-default">
+    return Safe(f"""<nav class="bg-neutral-primary-soft border-b border-default">
     <div class="max-w-(--breakpoint-xl) flex flex-wrap items-center justify-between mx-auto p-4">
         <a href="{reverse("games:index")}"
            class="flex items-center space-x-3 rtl:space-x-reverse">