Summary

_build_performance_tracker in app.py falls back to default PerformanceConfig() because RootConfig has no performance field. This means YAML-configured quality_judge_model, quality_judge_provider, and custom CI/LLM weights are ignored at auto-wiring time.

Acceptance Criteria

• Add performance: PerformanceConfig = Field(default_factory=PerformanceConfig) to RootConfig
• Update YAML config loader to parse the performance: section
• Pass effective_config.performance to _build_performance_tracker in create_app
• Update config design spec page
• Add tests for YAML round-trip of performance config fields

Context

Found during PR #1057 review. The auto-wiring code works correctly with defaults, but user-configured values in company YAML are not respected.

Design Spec Reference

• Operations page (providers/config section)
• Agents page SS8.3 (quality scoring config fields)