Add winner archive, host image upload and live demo data

Deliver the demo-ready feature set and seed data so the live site can be
presented end to end:

- Winner archive: ArchivedWinner domain, admin CRUD endpoints/view/manager
  and public archive surface, backed by AddArchivedWinners migration.
- Host presentation: host image upload and artist name on SiteSettings with
  public image endpoint and supporting migrations.
- Clip submissions: idempotent table-ensure migration plus current-season
  demo clips for review workflows.
- Demo seed data: sponsors, share links and 2025 archived winners, with a
  guarded RemoveDemoSeasons cleanup; all seeds guard against real data.
- EnsureRuntimeSchemaParity migration to align runtime schema defensively.
- Admin/home UI refinements; remove unused team role permissions modal and
  dead share-quick-links code.

All seed and schema migrations are idempotent (IF NOT EXISTS / ON CONFLICT)
and skip when real season data is present.

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

Backend/Endpoints/PublicWinnerArchiveEndpoints.cs

@@ -9,6 +9,42 @@ public static partial class PublicEndpoints
 {
     private static async Task<IResult> GetWinnerArchive(int year, AwardsDbContext db)
     {
+        var latestPublishedWinnerYear = await db.Results
+            .AsNoTracking()
+            .Where(result => result.Season.WinnersPublishedAt != null)
+            .Select(result => (int?)result.Season.Year)
+            .MaxAsync();
+
+        var archivedWinnerRows = await db.ArchivedWinners
+            .AsNoTracking()
+            .Where(item => item.Year == year)
+            .OrderBy(item => item.Category)
+            .ThenBy(item => item.Subcategory)
+            .ThenBy(item => item.WinnerName)
+            .ToArrayAsync();
+        if (archivedWinnerRows.Length > 0)
+        {
+            var archivedItems = archivedWinnerRows
+                .Select(item =>
+                {
+                    var metadata = SeasonMappings.InferProfileMetadataFromUrl(item.WinnerUrl, item.WinnerName);
+                    return new WinnerArchiveItemDto(
+                        item.Subcategory,
+                        item.Category,
+                        item.WinnerName,
+                        metadata.Slug,
+                        metadata.Platform,
+                        item.WinnerUrl,
+                        null,
+                        null,
+                        null,
+                        null);
+                })
+                .ToArray();
+
+            return Results.Ok(new WinnerArchiveResponse(year, archivedItems));
+        }
+
         var season = await db.Seasons
             .AsNoTracking()
             .Where(item => item.Year == year)
@@ -16,7 +52,7 @@ public static partial class PublicEndpoints
             .FirstOrDefaultAsync();
         if (season is null)
         {
-            return Results.NotFound();
+            return Results.Ok(new WinnerArchiveResponse(year, []));
         }
 
         if (season.WinnersPublishedAt is null)
@@ -24,11 +60,6 @@ public static partial class PublicEndpoints
             return Results.Ok(new WinnerArchiveResponse(year, []));
         }
 
-        var latestPublishedWinnerYear = await db.Results
-            .AsNoTracking()
-            .Where(result => result.Season.WinnersPublishedAt != null)
-            .Select(result => (int?)result.Season.Year)
-            .MaxAsync();
         if (latestPublishedWinnerYear == season.Year)
         {
             return Results.Ok(new WinnerArchiveResponse(year, []));