735e9c9312
- Add GeminiProvider with streaming and native tool calling - Support gemini-2.5-pro, gemini-2.0-flash, gemini-1.5-pro/flash models - Model-specific context window detection (1M-2M tokens) - Message conversion: assistant -> model role mapping - System messages extracted to system_instruction field - Tool schema conversion with functionCall/functionResponse parts - SSE streaming with JSON array buffer parsing - 8 unit tests for conversion and parsing logic - Register provider in g3-core and validate in g3-cli