Optimization Loop Performance Metrics

[ev-shindin]

Add timing and throughput metrics for the optimization loop.

Metrics:

wva_optimization_duration_seconds   histogram {status}
wva_models_processed_total          counter   {}

Implementation:

• Wrap optimize() with time.Since(start) observation
• Status labels: success, error, partial
• Histogram buckets: {0.01, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10} seconds
• Increment wva_models_processed_total for each model processed in a cycle

Acceptance Criteria:

• Duration histogram emitted per optimization cycle
• Models-processed counter incremented correctly
• Unit tests verify histogram observation and counter increment