feat(nodes): live CPU/RAM/disk monitoring in the node list

- node-agent: internal/metrics — read CPU% (GetSystemTimes), RAM (GlobalMemoryStatusEx),
  disk used%/total (GetDiskFreeSpaceEx) via stdlib kernel32 (no external dep; windows
  build + non-windows stub). Heartbeat now reports cpu_pct/ram_available_mb/disk_used_pct/
  disk_total_gb + ae_running.
- render-svc: heartbeat persists last_disk_pct + disk_total_gb (migration 29); RenderNode
  model + node SELECT/scan carry them.
- admin: rewrite NodesTable to the real RenderNode shape (fixes a pre-existing items/V2Node
  mismatch that left the list empty) + a CPU/RAM/disk bars column + stale-heartbeat flag.
- assets-bundle ingestion: ProjectMediaBundle (jszip) auto-maps project.zip → project/scene
  image/demo/colour + music; PatchProject gains image/full_demo/shared_colors_svg.
- scan: RGBA (4-number) colours recognised + frshare single-int controls detected.

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

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

@@ -398,6 +398,10 @@ public class TemplateService(ContentDbContext db)
         if (req.FreeFps.HasValue) project.FreeFps = req.FreeFps.Value;
         if (req.IsPublished.HasValue) project.IsPublished = req.IsPublished.Value;
         if (req.Sort.HasValue) project.Sort = req.Sort.Value;
+        // media/colour fields (set by the assets-bundle ingestion)
+        if (req.Image != null) project.Image = req.Image;
+        if (req.FullDemo != null) project.FullDemo = req.FullDemo;
+        if (req.SharedColorsSvg != null) project.SharedColorsSvg = req.SharedColorsSvg;
         project.UpdatedAt = DateTime.UtcNow;
 
         await db.SaveChangesAsync();