Map Bitget API error codes to internal solver errors

[squadgazzz]

Description

• Parse error_code and message fields from Bitget API responses (previously only status and data were parsed)
• Map Bitget error codes (80000–80010) to appropriate internal error variants:
  • NotFound: 80001 (insufficient balance), 80002 (below min), 80003 (above max), 80004 (expired), 80005 (no liquidity), 80008 (reverse quote), 80009 (token info), 80010 (price info)
  • BadRequest: 80006 (illegal request)
  • Api (logged): 80000 (internal), 80007 (partner invalid), unknown codes
• Handle HTTP 429 explicitly as RateLimited before the generic status check

Previously all non-zero status values except hardcoded 404/429 fell through to a generic Api error, which led to a lot of alert noise. The old 404/429 mapping in handle_api_error didn't match the actual Bitget API format (which uses status: 0/1 + error_code: 80xxx).

Error code reference: https://web3.bitget.com/en/docs/swap-order#error-code-list

How to test

• All 5 existing bitget tests pass (cargo nextest run -p solvers bitget)
• Updated not_found test to use the actual Bitget error response format (status: 1, error_code: 80005)

[gemini-code-assist]

Code Review

This pull request refactors Bitget API error handling to utilize specific error_code and message fields from the API response. This includes updating the Response DTO, modifying the handle_api_error function to process these new fields, introducing a BadRequest error type, and updating the Error enum and its conversions. Test cases have also been adjusted to reflect the new error response structure. I have no feedback to provide.

[gemini-code-assist]

Code Review

This pull request refactors the Bitget API error handling to utilize more granular error codes and messages. The Response DTO now includes error_code and message fields, and the handle_api_error function has been updated to parse these new fields, mapping specific Bitget error codes to internal NotFound and BadRequest error types. The Error enum and its conversion from bitget::Error have been adjusted, and the request function now explicitly handles rate limiting and passes the new error details. A test case was also updated to reflect the new error response format. The review suggests an improvement to the handle_api_error function's message parameter, recommending it be changed from String to Option<String> to enhance efficiency by avoiding unnecessary allocations, along with corresponding updates to its call sites.

[squadgazzz]

The failing audit is fixed in #4286