Add Cloudflare deploy button and auto-size model panel

[vdeng-ai]

Changes

• Add official Deploy to Cloudflare buttons to English and Chinese READMEs.
• Document automatic Wrangler resource provisioning and required public-deployment secrets.
• Remove the viewport-sized minimum height from the Models panel so it ends naturally after the model list and Add Model row.
• Keep History's existing full-workspace height behavior unchanged.

Runtime impact

• No API, Worker, polling, persistence, KV access pattern, or Cloudflare runtime behavior changes.
• The model-height fix is CSS-only; README changes are documentation-only.