chore: remove Google provider entirely

fix(google): match OpenAI finish_reason format exactly

fix(google): finish_reason only in final SSE chunk

fix(google): buffer non-streaming JSON, convert to fake SSE chunks

fix(google): strip repetition_penalty and top_k from request body

fix(google): force non-streaming to bypass HF Spaces HTTP/2 edge bug

fix(google): strip extra_content/thought_signature from SSE chunks

fix(google): strip unsupported params from request body

fix(streaming): decompress upstream chunks for Google SSE

clean error messages, add model validation, add gemini-3.1-flash-lite

fix streaming: async generator keeps httpx client alive internally

fix streaming: use client.send() with stream=True instead of context manager

fix httpx streaming: use client.stream() for async SSE

feat: add OpenAI-compatible API proxy with NVIDIA and Google integration