Improve admin candidate modal UX and add clip menu visibility toggle

- Widen AdminCandidateEditorModal to size lg for better readability
- Rename "Clip-Compilation" section to "Clip / Compilation", update copy to reflect single clips too, drop upload hint and Clip-Plattform field, rename label to "Link"
- Fix NativeSelect dropdown clipping inside overflow-y-auto modals by teleporting the menu to body with fixed positioning, flip-up logic, and dynamic maxHeight capped to viewport
- Add ClipAdminMenuVisible setting (backend domain, contracts, endpoint, migration) with matching frontend types, defaults, form wiring, and toggle in the Clip-Workflow modal — hides the Clips nav item from the admin sidebar when disabled

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Backend/Endpoints/PublicWinnerArchiveEndpoints.cs

@@ -35,6 +35,10 @@ public static partial class PublicEndpoints
                 WinnerName = result.Candidate.DisplayName,
                 WinnerSlug = result.Candidate.ChannelSlug,
                 WinnerPlatform = result.Candidate.Platform,
+                ClipUrl = result.Candidate.ClipCompilationUrl,
+                ClipTitle = result.Candidate.ClipCompilationTitle,
+                ClipPlatform = result.Candidate.ClipCompilationPlatform,
+                ClipEmbedStatus = result.Candidate.ClipEmbedStatus,
             })
             .ToArrayAsync();
 
@@ -44,7 +48,11 @@ public static partial class PublicEndpoints
                 result.WinnerName,
                 result.WinnerSlug,
                 result.WinnerPlatform,
-                SeasonMappings.BuildProfileUrl(result.WinnerPlatform, result.WinnerSlug)))
+                SeasonMappings.BuildProfileUrl(result.WinnerPlatform, result.WinnerSlug),
+                result.ClipUrl,
+                result.ClipTitle,
+                result.ClipPlatform,
+                result.ClipEmbedStatus))
             .ToArray();
 
         return Results.Ok(new WinnerArchiveResponse(year, items));