reference: https://api-docs.deepseek.com/

Release Notes:

- Added deepseek-v4-pro and deepseek-v4-flash models

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Signed-off-by: Xiaobo Liu <cppcoffee@gmail.com>
Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>
Co-authored-by: MrSubidubi <dev@bahn.sh>