feat(render): full-screen render page, one-active-render limit, app-wide progress

Concurrent-render ceiling (a user runs 1 render at a time unless granted more):
- Identity: TokenService emits max_renders claim from User.ParallelRenderingCeiling
- Identity: admin POST /v1/users/{id}/render-slots (AdminService.SetRenderSlotsAsync,
  clamped 1..50) — gamification or admin raises a user's ceiling
- render-svc: middleware reads max_renders (default 1); CreateJob rejects with 409
  active_render_limit when active jobs >= ceiling
- render-svc: db.CountActiveJobs + ListActiveJobs; GET /v1/renders/active returns
  in-flight renders + can_start_new

Full-screen render page (replaces the modal):
- /studio/render/[projectId]: config (resolution/fps) → live preview + progress →
  download; resumes this project's in-flight render on mount; blocks when another
  render is active; reads ?preset=
- StudioTopBar export menu now navigates to the page; RenderModal deleted (dead)

App-wide minimal progress:
- GlobalRenderProgress pill mounted in the locale layout for authed users; polls
  /api/render/active every 4s, shows thumbnail + step + % on every page, click →
  the render page; hidden on the render page and when idle

Admin: UserActions gains a "concurrent render slots" control.

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

services/render/internal/handlers/renders.go

@@ -54,6 +54,39 @@ func (h *RenderHandler) List(c *gin.Context) {
 	})
 }
 
+// GET /v1/renders/active
+// Lightweight list of the user's in-flight renders + their ceiling — powers the
+// app-wide mini progress widget and the "can I start another render?" check.
+func (h *RenderHandler) Active(c *gin.Context) {
+	userID := middleware.GetUserID(c)
+	jobs, err := h.store.ListActiveJobs(c.Request.Context(), userID)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, models.APIError{Code: "internal_error", Message: err.Error()})
+		return
+	}
+	if jobs == nil {
+		jobs = []*models.RenderJob{}
+	}
+	out := make([]gin.H, 0, len(jobs))
+	for _, j := range jobs {
+		out = append(out, gin.H{
+			"id":               j.ID,
+			"saved_project_id": j.SavedProjectID,
+			"name":             j.Name,
+			"step":             j.Step,
+			"render_progress":  j.RenderProgress,
+			"preview_b64":      j.ImagePreviewB64,
+			"created_at":       j.CreatedAt,
+		})
+	}
+	maxRenders := middleware.GetMaxRenders(c)
+	c.JSON(http.StatusOK, gin.H{
+		"active":       out,
+		"max_renders":  maxRenders,
+		"can_start_new": len(out) < maxRenders,
+	})
+}
+
 // POST /v1/renders
 func (h *RenderHandler) Create(c *gin.Context) {
 	userID := middleware.GetUserID(c)
@@ -65,6 +98,20 @@ func (h *RenderHandler) Create(c *gin.Context) {
 		return
 	}
 
+	// Concurrent-render ceiling: a user may run only `max_renders` renders at once
+	// (default 1; raised by gamification level or an admin grant via the JWT claim).
+	maxRenders := middleware.GetMaxRenders(c)
+	active, err := h.store.CountActiveJobs(c.Request.Context(), userID)
+	if err != nil {
+		log.Printf("count active jobs failed (allowing render): %v", err)
+	} else if active >= maxRenders {
+		c.JSON(http.StatusConflict, models.APIError{
+			Code:    "active_render_limit",
+			Message: "شما یک رندر در حال انجام دارید. برای شروع رندر جدید صبر کنید تا رندر فعلی کامل شود.",
+		})
+		return
+	}
+
 	// Daily render-limit: consume one render charge (0 max = unlimited).
 	allowed, err := h.identity.Consume(c.Request.Context(), userID)
 	if err != nil {