feat(gemini): add Gemini thinking configuration support and metadata normalization
- Introduced logic to parse and apply `thinkingBudget` and `include_thoughts` configurations from metadata.
- Enhanced request handling to include normalized Gemini model metadata, preserving the original model identifier.
- Updated Gemini and Gemini-CLI executors to apply thinking configuration based on metadata overrides.
- Refactored handlers to support metadata extraction and cloning during request preparation.
When from==to (Claude→Claude scenario), directly forward SSE stream
line-by-line without invoking TranslateStream. This preserves the
multi-line SSE event structure (event:/data:/blank) and prevents
JSON parsing errors caused by event fragmentation.
Resolves: JSON parsing error when using Claude Code streaming responses
fix: correct SSE event formatting in Handler layer
Remove duplicate newline additions (\n\n) that were breaking SSE event format.
The Executor layer already provides properly formatted SSE chunks with correct
line endings, so the Handler should forward them as-is without modification.
Changes:
- Remove redundant \n\n addition after each chunk
- Add len(chunk) > 0 check before writing
- Format error messages as proper SSE events (event: error\ndata: {...}\n\n)
- Add chunkIdx counter for future debugging needs
This fixes JSON parsing errors caused by malformed SSE event streams.
fix: update comments for clarity in SSE event forwarding
- Replaced `config.Config` with `config.SDKConfig` across components for simpler configuration management.
- Updated proxy setup functions and handlers to align with `SDKConfig` improvements.
- Reorganized handler imports to match new SDK structure.
