enable tool support

[michaelmdeng]

All models support tool calling, but this info isn't available in the https://api.deepseek.com/models API so hard-code it for now

$ llm models list -q deepseek --options
DeepSeek: deepseek-coder
  Options:
    temperature: float
    max_tokens: int
    top_p: float
    frequency_penalty: float
    presence_penalty: float
    stop: str
    logit_bias: dict, str
    seed: int
    json_object: boolean
  Features:
  - streaming
  - tools
  - async
  Keys:
    key: deepseek
    env_var: LLM_DEEPSEEK_KEY
DeepSeek: deepseek-reasoner
  Options:
    temperature: float
    max_tokens: int
    top_p: float
    frequency_penalty: float
    presence_penalty: float
    stop: str
    logit_bias: dict, str
    seed: int
    json_object: boolean
  Features:
  - streaming
  - tools
  - async
  Keys:
    key: deepseek
    env_var: LLM_DEEPSEEK_KEY

$ llm -m deepseek-chat --tool llm_version "What version of LLM is this?" --td

Tool call: llm_version({})
  0.26

The installed version of LLM is 0.26.