feat(optimization): consolidate extraction pipeline and metrics

- Flatten directory structure by moving masking and evals to scripts root.
- Merge evaluation metrics into scripts/optimization/evals.
- Restore and verify extraction tests for the new structure.

scripts/optimization/extract.ts

@@ -7,7 +7,7 @@
 import * as fs from 'node:fs';
 import * as path from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { maskVariables } from './lib/masking.js';
+import { maskVariables } from './masking.js';
 
 export interface OptimizationTarget {
   id: string;