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/db/db.go

@@ -371,6 +371,45 @@ func (s *Store) GetJobByID(ctx context.Context, id, userID uuid.UUID) (*models.R
 	return jobs[0], nil
 }
 
+// CountActiveJobs returns how many non-terminal render jobs the user currently has.
+// Used to enforce the per-user concurrent-render ceiling.
+func (s *Store) CountActiveJobs(ctx context.Context, userID uuid.UUID) (int, error) {
+	var n int
+	err := s.pool.QueryRow(ctx, `
+		SELECT COUNT(*) FROM render.render_jobs
+		WHERE user_id = $1
+		  AND step NOT IN ('Done'::render_step, 'Failed'::render_step, 'Cancelled'::render_step)`,
+		userID).Scan(&n)
+	return n, err
+}
+
+// ListActiveJobs returns the user's in-flight render jobs (most recent first),
+// lightweight projection for the app-wide mini progress widget.
+func (s *Store) ListActiveJobs(ctx context.Context, userID uuid.UUID) ([]*models.RenderJob, error) {
+	rows, err := s.pool.Query(ctx, `
+		SELECT id, saved_project_id, name, step, render_progress, image_preview_b64, created_at
+		FROM render.render_jobs
+		WHERE user_id = $1
+		  AND step NOT IN ('Done'::render_step, 'Failed'::render_step, 'Cancelled'::render_step)
+		ORDER BY created_at DESC`,
+		userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var out []*models.RenderJob
+	for rows.Next() {
+		j := &models.RenderJob{}
+		if err := rows.Scan(&j.ID, &j.SavedProjectID, &j.Name, &j.Step,
+			&j.RenderProgress, &j.ImagePreviewB64, &j.CreatedAt); err != nil {
+			return nil, err
+		}
+		out = append(out, j)
+	}
+	return out, rows.Err()
+}
+
 func (s *Store) CreateJob(ctx context.Context, userID, tenantID uuid.UUID, req *models.RenderJobCreateRequest) (*models.RenderJob, error) {
 	priceType := "Free"
 	if req.PriceType != nil {