feat: add query parameter support for OpenAI-compatible providers

[Awowen]

Summary

Adds a queryParams option to OpenaiCompatibleProviderSettings that appends query parameters to all API requests.

• Added queryParams?: Record<string, string> to provider settings
• Created getUrl helper to construct URLs with query params
• Added integration tests for the new functionality

Fixes #7198

Test plan

• [x] Added integration tests for providers with queryParams
• [x] Verified providers without queryParams still work
• [x] Ran bun test test/provider/openai-compatible.test.ts - all pass