5c112b40bf
Sets the `deepseek-cn` provider preset's default `base_url` to the official host (`https://api.deepseek.com`) per [api-docs.deepseek.com](https://api-docs.deepseek.com/). Keeps recognizing `api.deepseeki.com` in URL heuristics and chat-client normalization so existing configs continue to work, and updates the `doctor` strict-tool-mode endpoint hint, docs, and examples accordingly. Closes #1079. Thanks to @Jefsky for the fix.