feat(v2): add safe AI fallback and cache/reanalysis decision

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

logic/fallback.test.js

@@ -0,0 +1,12 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const { buildFallbackClassification } = require('./fallback');
+
+test('fallback e sempre seguro e marcado como tal', () => {
+  const result = buildFallbackClassification('ai_timeout');
+  assert.equal(result.is_fallback, true);
+  assert.equal(result.fallback_reason, 'ai_timeout');
+  assert.equal(result.confidence, 0);
+  assert.equal(result.classification, 'ACTIONABLE_NOW');
+  assert.ok(result.reason.includes('Fallback'));
+});