feat(prompt-optimization): implement multi-objective evaluation metrics

Established a Pareto-ready evaluation foundation for the Genetic-Pareto (GEPA)
optimizer, supporting simultaneous optimization of accuracy and density.

Key improvements:
- Core Architecture: Defined standardized `MetricResult` and `OptimizationDirection`
  types in `packages/core/src/evals/types.ts` to support multi-objective fitness.
- Centralized Config: Implemented `packages/core/src/evals/config.ts` with tunable
  weights and detailed documentation for scoring gradients.
- Tool Alignment Metric: Created `metrics/toolAlignment.ts` to measure functional
  accuracy, argument precision, and explicit shell avoidance.
- Token Frugality Metric: Created `metrics/tokenFrugality.ts` to measure and
  penalize conversational noise ("chatter") using a configurable threshold.
- Verification Suite: Added comprehensive unit tests for all metrics, achieving
  100% coverage of scoring logic and gradient steps.
- Project Integration: Relocated `schema.ts` to the core package for build safety,
  updated the data validator, and extended project-wide lint/format scripts.

scripts/validate-data.ts

@@ -6,7 +6,7 @@
 
 import * as fs from 'node:fs';
 import * as path from 'node:path';
-import type { Scenario } from '../data/schema.ts';
+import type { Scenario } from '../packages/core/src/evals/schema.ts';
 
 const MANIFEST_FILE = 'data/manifest.json';
 const DEFAULT_DATA_DIR = 'data';