Carry the Cloudflare Images binding (IMAGES) for Astro #222

@astrojs/cloudflare 14 turns on image processing through an IMAGES Images binding by default. rustybuns.config.ts has no images binding type, so init (#200) leaves it out: pages, API routes and KV work on the edge and desktop, but on-demand image transforms will not.

Done when there is an images binding (edge: Cloudflare Images; desktop/box: a passthrough), and init adds it for Astro apps whose config doesn't set imageService to compile or passthrough.