refactor: restructure to clean architecture

fix: restore ScoringConfig improvements lost in refactor commit

docs: rewrite README and CLAUDE.md to reflect current architecture

code-format

code fixes

tests/RuleMerger.test.js

@@ -0,0 +1,66 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { RuleMerger } from '../src/screener/RuleMerger.js';
+import { SCORE_MODE } from '../src/config/constants.js';
+
+const ctx = {
+  benchmarks: { marketPE: 25, techPE: 32, reitYield: 3.8, igSpread: 1.2 },
+};
+
+test('FUNDAMENTAL mode returns Graham-style P/E gate', () => {
+  const rules = RuleMerger.getRulesForAsset(
+    'STOCK',
+    { sector: 'GENERAL' },
+    ctx,
+    SCORE_MODE.FUNDAMENTAL,
+  );
+  assert.equal(rules.gates.maxPERatio, 15); // updated: Graham's real rule is 15x
+  assert.equal(rules.gates.maxPegGate, 1.0); // updated: Lynch PEG standard
+});
+
+test('INFLATED mode loosens P/E gate from live SPY data', () => {
+  const rules = RuleMerger.getRulesForAsset(
+    'STOCK',
+    { sector: 'GENERAL' },
+    ctx,
+    SCORE_MODE.INFLATED,
+  );
+  assert.equal(rules.gates.maxPERatio, Math.round(25 * 1.5)); // 37
+  assert(rules.gates.maxPERatio > 15, 'Inflated P/E should exceed fundamental 15x');
+});
+
+test('INFLATED tech P/E gate uses XLK benchmark', () => {
+  const rules = RuleMerger.getRulesForAsset(
+    'STOCK',
+    { sector: 'TECHNOLOGY' },
+    ctx,
+    SCORE_MODE.INFLATED,
+  );
+  assert.equal(rules.gates.maxPERatio, Math.round(32 * 1.3)); // 42
+});
+
+test('Sector override applied before inflated overrides', () => {
+  const rules = RuleMerger.getRulesForAsset(
+    'STOCK',
+    { sector: 'REIT' },
+    ctx,
+    SCORE_MODE.FUNDAMENTAL,
+  );
+  assert.equal(rules.gates.maxPERatio, 9999);
+  assert.equal(rules.weights.yield, 5);
+  assert.equal(rules.weights.margin, 0);
+});
+
+test('SECTOR_OVERRIDE is deleted from returned rules', () => {
+  const rules = RuleMerger.getRulesForAsset(
+    'STOCK',
+    { sector: 'GENERAL' },
+    ctx,
+    SCORE_MODE.FUNDAMENTAL,
+  );
+  assert.equal(rules.SECTOR_OVERRIDE, undefined);
+});
+
+test('throws for unknown asset type', () => {
+  assert.throws(() => RuleMerger.getRulesForAsset('CRYPTO', {}, ctx), /No rules configured/);
+});