Add header-based configuration override for QuickNode integration

[odysseus0]

Summary

• Implements X-Flashbots-Origin header support for guaranteed refund collection
• Adds preset configuration system to ensure partners receive fixed refund percentages
• Maintains backward compatibility with existing URL parameter flows

Implementation Details

• ConfigurationWatcher: Extended to support presets field with graceful error handling
• Request Handler: New getEffectiveParameters() method checks header first, falls back to URL parsing
• Configuration: Preset URLs are pre-parsed at startup for performance and early error detection

Key Behavior

When X-Flashbots-Origin header is present:

1. Looks up preset configuration for the origin ID
2. Uses preset parameters, completely ignoring URL parameters
3. Falls back to normal URL parsing if no preset found

Testing

• Unit tests cover preset parsing and header override logic
• Tests graceful degradation for invalid preset configurations
• Ready for testnet deployment and integration testing

Configuration Changes Required

For Testing (Sepolia testnet)

Add to devops/k8s/eth-l1-testnets/sepolia/protect/rpc/configs/customers.yaml:

urls:
  test1:
    - /fast?originId=test1
  test2:
    - /fast?originId=test2&auctionTimeout=500&maxBlockRange=7
presets:
  test-header: /fast?originId=test-header&refund=0xb60e8dd61c5d32be8058bb8eb970870f07233155:50

For Production (when QuickNode provides requirements)

Add to devops/k8s/eth-l1-prod/protect-old/rpc.yaml:

urls:
  # ... existing configs ...
  quicknode:
    - /fast?originId=quicknode
presets:
  quicknode: [QuickNode to provide: endpoint, refund address, percentage, other params]

Testing Plan

1. Deploy testnet config changes
2. Deploy code to testnet
3. Test with header: X-Flashbots-Origin-ID: test-header
4. Verify preset overrides URL parameters correctly
5. Verify fallback works when no header present

🤖 Generated with Claude Code

[jeyldii]

LGTM 🚀