fix(types): expose tool call id on Message.ToolCall

[winklemad]

What & why

The Ollama server returns an id on each tool call in the response, e.g. {"id": "call_p7o2gz50", "function": {...}}. But Message.ToolCall has no id field, so it's silently dropped — and it isn't in model_extra either — leaving no way to read the tool-call id from Python (#667). That id is needed to correlate a tool call with its result.

Change

Add an optional id: Optional[str] = None to Message.ToolCall. It's optional/defaulted so responses that omit it (older servers) keep parsing unchanged.

Testing

tests/test_type_serialization.py: the id round-trips from a raw response and serializes back via model_dump(), and defaults to None when absent. Full suite: 94 passed. ruff check + ruff format clean.

Fixes #667

[vaderollama]

LGTM — adds the missing id field to Message.ToolCall matching the Go API (ToolCall.Id in api/types.go). Backwards-compatible (optional, defaults to None), tests cover round-tripping and default. Resolves #667.

@ParthSareen — ready to merge.