feat: add Cerebras AI support

[egoist]

Adds support for Cerebras AI in the ai-proxy service.

Changes

• Added Cerebras proxy configuration to route /cerebras/* to https://api.cerebras.ai
• Updated README.md with Cerebras usage example
• Follows same pattern as other AI provider integrations

Closes #7

Generated with Claude Code

[claude]

Claude finished @egoist's task —— View job

---

PR Review: Cerebras AI Support

✅ Review Summary

This PR successfully adds Cerebras AI support following the established patterns in the codebase. The implementation is clean, consistent, and poses no concerns.

Code Quality & Best Practices ✅

• Perfect consistency: The Cerebras configuration follows the exact same pattern as other AI providers in the proxies array (main.ts:92-94)
• Clean structure: Alphabetically placed among providers, maintains code organization
• Documentation: README.md properly updated with usage example (README.md:37-39)

Security Review ✅

• HTTPS endpoint: Uses secure https://api.cerebras.ai target
• Standard proxy logic: Leverages the same battle-tested proxy implementation used by all other providers
• Header filtering: Benefits from existing security measures (filters out CF headers, forwarded headers, etc.)

Performance Considerations ✅

• Zero performance impact: Simply adds another route option to existing proxy logic
• Same timeout handling: Uses the existing 60-second timeout and fetchWithTimeout utility
• Consistent resource usage: No additional overhead beyond what other providers require

Potential Issues ✅

• No bugs identified: Implementation is straightforward and follows proven patterns
• Path handling: Correctly uses /cerebras/ path segment with proper URL rewriting
• Error handling: Inherits robust error handling from existing proxy infrastructure

Test Coverage ⚠️

• No tests found: The project currently has no test suite, so this change is consistent with the existing approach
• Manual testing recommended: Consider testing the new endpoint manually to ensure Cerebras API compatibility

Recommendations

1. Ready to merge: This is a clean, low-risk addition that maintains code consistency
2. Future consideration: The project would benefit from adding integration tests for all AI provider endpoints
3. Verification: Test that Cerebras API calls work correctly through the new /cerebras/* route

Overall: This is exactly how new AI provider support should be added to this project. Well done! 🎯

---

Review completed - All requested criteria analyzed and no blocking issues found.