fix(models): forward Anthropic generation config

[MukundaKatta]

Summary

• forward temperature, top_p, top_k, and stop_sequences from GenerateContentConfig to Anthropic messages.create(...)
• apply the same forwarding in the streaming path
• add regression tests for both non-streaming and streaming kwargs

Testing

• python3 -m py_compile src/google/adk/models/anthropic_llm.py tests/unittests/models/test_anthropic_llm.py
• python3 -m pytest tests/unittests/models/test_anthropic_llm.py -k "forwards_generation_config_kwargs or finish_reason or non_streaming_does_not_pass_stream_param" (fails during local collection: ModuleNotFoundError: No module named anthropic)

[adk-bot]

Response from ADK Triaging Agent

Hello @MukundaKatta, thank you for creating this PR!

This PR seems to be a feature enhancement. Could you please associate a GitHub issue with this PR? If there is no existing issue, could you please create one? This information will help reviewers to review your PR more efficiently. Thanks!

[rohityan]

Hi @MukundaKatta , Thank you for your contribution! We appreciate you taking the time to submit this pull request. Please fix formatting errors by running autoformat.sh