Add list styles: Podium, Spotlight, Grid, List

- Each list picks a style in List settings (new lists default to Podium);
  existing lists keep Grid or List
- Podium: top 3 on medal-colored steps (#1 center and raised), the rest
  behind a native <details> "Show N more"; stacks #1 over #2/#3 on phones
- Spotlight: #1 as a feature card (art, why-note or description, play
  button), the rest as a numbered list
- Visitors can switch styles on a list page (?style=), preserved across
  pages; later pages fall back to a plain list since they don't start at #1
- Entries' detail data now lives on a wrapper per list, so featured and
  collapsed entries all open the detail view

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/admin.go

@@ -44,6 +44,7 @@ func (s *Server) handleAdminLists(w http.ResponseWriter, r *http.Request) {
 	s.render(w, r, http.StatusOK, "admin_lists", "Your lists", adminPage{Boot: bootJSON(map[string]any{
 		"lists":      lists,
 		"covers":     covers,
+		"styles":     store.ListStyles,
 		"categories": store.Categories,
 		"limits":     limits,
 	})})
@@ -72,6 +73,7 @@ func (s *Server) handleAdminList(w http.ResponseWriter, r *http.Request) {
 		"limits":      limits,
 		"provider":    provider,
 		"productions": store.TheaterProductions,
+		"styles":      store.ListStyles,
 		"pageSize":    listPageSize,
 	})})
 }