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/Contracts/AdminSeasonContracts.cs

@@ -23,7 +23,13 @@ public sealed record AdminCandidateItemDto(
     int CategoryId,
     string DisplayName,
     string ChannelSlug,
-    string Platform);
+    string Platform,
+    string AcceptanceStatus,
+    string? AcceptanceNote,
+    string? ClipCompilationUrl,
+    string? ClipCompilationTitle,
+    string? ClipCompilationPlatform,
+    string ClipEmbedStatus);
 
 public sealed record AdminAwardResultItemDto(
     int Id,
@@ -102,7 +108,13 @@ public sealed record UpsertCandidateRequest(
     int CategoryId,
     string DisplayName,
     string ChannelSlug,
-    string Platform);
+    string Platform,
+    string? AcceptanceStatus = null,
+    string? AcceptanceNote = null,
+    string? ClipCompilationUrl = null,
+    string? ClipCompilationTitle = null,
+    string? ClipCompilationPlatform = null,
+    string? ClipEmbedStatus = null);
 
 public sealed record SetAwardResultRequest(
     int CategoryId,