v0.14.1

Adds forced tool choice, which Groq was missing since it was left out of the v0.13 release. Until now it accepted the toolChoice option and silently dropped it.

Groq's API is OpenAI-compatible, so the mapping matches deepseek and openai:

toolChoice	Sent as
'auto'	"auto"
'none'	"none"
'required'	"required"
['name' => 'x']	{"type":"function","function":{"name":"x"}}

Validation lives in core's ToolChoice::fromOption() and throws before any HTTP call. Additive and backward compatible: omitting the option sends nothing, exactly as before.