feat(errors): add network error classification with user-friendly messages (#53)

chore: add debug log before sending request to Kiro API

fix: add Connection: close header for streaming requests (#38)

fix(http): add shared HTTP client with connection pooling (#24)

refactor: rename OpenAI-specific modules with _openai suffix

refactor: update kiro_gateway naming to kiro

refactor: rename kiro_gateway to kiro