Shape, on a photograph block

Choose 16:9 and the band gets shorter than the picture — the ratio becomes a slot
shape and the site serves a rendition cut to it, rather than a whole photograph
scaled down by the browser.

`setContent` writes the whole content object, because the API replaces it rather
than merging: a PATCH with `{ ratio }` alone would drop the url.

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

web/canvas.ts

@@ -62,7 +62,7 @@ export type CanvasComponent = {
     would then need a cast, and the point of naming them is that the compiler knows `free-text` holds
     `html` and `gallery` holds `galleryId`.
   */
-  content?: { html?: string; galleryId?: number | null; url?: string };
+  content?: { html?: string; galleryId?: number | null; url?: string; ratio?: number; crop?: string };
   padding?: Record<string, { x?: number; y?: number }>;
 };
 export type CanvasSection = {