selecting a band opens its settings

Name and Title, in the editor column — the band row in the nav had only scrolled
the preview until now.

Both, not the title alone: a form showing one of two names invites somebody to
change the wrong one, and `name` could only be set when the band was created.

Last in the editor's order, so a block or a spacing editor wins — those were
opened deliberately, and the band is merely still selected underneath them.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/canvas.ts

@@ -64,6 +64,8 @@ export type CanvasComponent = {
 export type CanvasSection = {
   id: number;
   name: string;
+  /** The heading the page draws above the band, or null. Not `name` — see the site's schema. */
+  title?: string | null;
   layout: 'one' | 'two';
   padding?: Record<string, { x?: number; y?: number }>;
   components: CanvasComponent[];