- Updated `ConvertGeminiRequestToClaude`, `ConvertGeminiRequestToCodex`, and their respective response counterparts to include logic for retaining and using tool/call IDs when present from gateway-provided inputs.
- Enhanced pairing logic between function calls and responses to handle custom and auto-generated IDs consistently.
- Introduced tests validating ID preservation and proper behavior in both streaming and non-streaming flows.
Closes: #3878
