Gemini deprecates temperature, top_p, and top_k

Applications can silently lose sampling control now and later begin failing if shared generation configs continue to include these fields.

Recommended action: Strip temperature, top_p, and top_k from Gemini requests and encode response constraints in a clear system instruction.

Affected: gemini-3.6-flash, gemini-3.5-flash-lite, temperature, top_p, top_k, generation_config, GenerateContentConfig