fix(render): node reports progress → moving bar + ETA (was stuck 0%/Preparing)

The node's onProgress callback only LOGGED — it never POSTed, so render_progress stayed
0 and step stayed Preparing (no bar, no ETA). Add render-svc POST
/v1/internal/render/jobs/{id}/progress (UpdateJobProgress: set render_progress + bump
step Queued/Preparing→Rendering once >0) + client UpdateProgress + wire onProgress to
post it (8s best-effort timeout, AE-CPU/DB-starvation tolerant). Preview already posts;
real-frame preview is epic C.

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

services/render/cmd/server/main.go

@@ -197,6 +197,7 @@ func main() {
 		internal.POST("/nodes/:node_id/fonts/:request_id/status", fontH.Report)
 		internal.POST("/render/jobs/claim", internalH.Claim)
 		internal.POST("/render/jobs/:job_id/preview", internalH.Preview)
+		internal.POST("/render/jobs/:job_id/progress", internalH.RenderProgress)
 		internal.POST("/render/jobs/:job_id/output-upload-url", internalH.OutputUploadURL)
 		internal.POST("/render/jobs/:job_id/frames", internalH.FrameProgress)
 		internal.POST("/render/jobs/:job_id/complete", internalH.Complete)