fix(templates): real scene count on template pages (was always 0)

The card + detail read template.sceneCount, but the API never sent one — so the
frontend mapper hardcoded sceneCount:0 for every DB-backed template.

- content-svc: ContainerSummaryResponse + ContainerDetailResponse now carry
  SceneCount. The list computes it with one grouped query (scenes per aspect project,
  max across aspects); the detail loads scenes and counts them.
- frontend: V2ContainerSummary.scene_count → AdminProject.sceneCount → the catalog
  card/detail (adminProjectToCatalogTemplate no longer hardcodes 0).

Verified on the live local API: fr-instagram-promo → 5, single-scene templates → 1.

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

services/content/FlatRender.ContentSvc/Application/Services/TemplateService.cs

@@ -51,8 +51,18 @@ public class TemplateService(ContentDbContext db)
         var total = await q.LongCountAsync();
         var items = await q.Skip((req.Page - 1) * req.PageSize).Take(req.PageSize).ToListAsync();
 
+        // Scene count per template = scenes in a single aspect project (max across
+        // projects). One grouped query, no scene entities loaded.
+        var ids = items.Select(i => i.Id).ToList();
+        var sceneCounts = (await db.Projects
+                .Where(p => p.DeletedAt == null && ids.Contains(p.ContainerId))
+                .Select(p => new { p.ContainerId, Cnt = p.Scenes.Count(s => s.DeletedAt == null) })
+                .ToListAsync())
+            .GroupBy(x => x.ContainerId)
+            .ToDictionary(g => g.Key, g => g.Max(x => x.Cnt));
+
         return new PagedResponse<ContainerSummaryResponse>(
-            items.Select(MapContainerSummary),
+            items.Select(c => MapContainerSummary(c, sceneCounts.GetValueOrDefault(c.Id, 0))),
             new PaginationMeta(req.Page, req.PageSize, total, (int)Math.Ceiling((double)total / req.PageSize))
         );
     }
@@ -62,7 +72,7 @@ public class TemplateService(ContentDbContext db)
         var container = await db.ProjectContainers
             .Include(x => x.ContainerCategories).ThenInclude(x => x.Category)
             .Include(x => x.ContainerTags).ThenInclude(x => x.Tag)
-            .Include(x => x.Projects.Where(p => p.DeletedAt == null))
+            .Include(x => x.Projects.Where(p => p.DeletedAt == null)).ThenInclude(p => p.Scenes.Where(s => s.DeletedAt == null))
             .FirstOrDefaultAsync(x => x.Slug == slug)
             ?? throw new KeyNotFoundException($"Container '{slug}' not found");
 
@@ -74,7 +84,7 @@ public class TemplateService(ContentDbContext db)
         var container = await db.ProjectContainers
             .Include(x => x.ContainerCategories).ThenInclude(x => x.Category)
             .Include(x => x.ContainerTags).ThenInclude(x => x.Tag)
-            .Include(x => x.Projects.Where(p => p.DeletedAt == null))
+            .Include(x => x.Projects.Where(p => p.DeletedAt == null)).ThenInclude(p => p.Scenes.Where(s => s.DeletedAt == null))
             .FirstOrDefaultAsync(x => x.Id == id)
             ?? throw new KeyNotFoundException($"Container {id} not found");
 
@@ -450,12 +460,13 @@ public class TemplateService(ContentDbContext db)
         await db.SaveChangesAsync();
     }
 
-    private static ContainerSummaryResponse MapContainerSummary(ProjectContainer c) => new(
+    private static ContainerSummaryResponse MapContainerSummary(ProjectContainer c, int sceneCount = 0) => new(
         c.Id, c.Slug, c.Name, c.Description, c.Image, c.Demo, c.MiniDemo,
         c.IsPublished, c.IsPremium, c.IsMockup, c.PrimaryMode.ToString(),
         c.RateAvg, c.RateCount, c.ViewCount, c.UseCount, c.Sort, c.SortDate,
         c.ContainerCategories.Select(cc => cc.Category.Slug).ToList(),
-        c.ContainerTags.Select(ct => ct.Tag.Name).ToList()
+        c.ContainerTags.Select(ct => ct.Tag.Name).ToList(),
+        sceneCount
     );
 
     private static ContainerDetailResponse MapContainerDetail(ProjectContainer c) => new(
@@ -465,7 +476,8 @@ public class TemplateService(ContentDbContext db)
         c.RateAvg, c.RateCount, c.ViewCount, c.UseCount, c.Sort, c.SortDate,
         c.Projects.Select(MapProject).ToList(),
         c.ContainerCategories.Select(cc => MapCategoryFlat(cc.Category)).ToList(),
-        c.ContainerTags.Select(ct => new TagResponse(ct.Tag.Id, ct.Tag.Name, ct.Tag.LatinName, ct.Tag.Slug, ct.Tag.AppliesToMode, ct.Tag.IsActive)).ToList()
+        c.ContainerTags.Select(ct => new TagResponse(ct.Tag.Id, ct.Tag.Name, ct.Tag.LatinName, ct.Tag.Slug, ct.Tag.AppliesToMode, ct.Tag.IsActive)).ToList(),
+        c.Projects.Count == 0 ? 0 : c.Projects.Max(p => p.Scenes.Count)
     );
 
     private static CategoryResponse MapCategoryFlat(Category c) => new(