docs: add work log for 2026-06-15 and update DB deletion policy in README

scratch/analyze_codes.cjs

@@ -0,0 +1,24 @@
+const mysql = require('mysql2/promise');
+require('dotenv').config();
+
+async function analyzeCodes() {
+  const connection = await mysql.createConnection({
+    host: process.env.DB_HOST,
+    user: process.env.DB_USER,
+    password: process.env.DB_PASS,
+    database: process.env.DB_NAME,
+    port: parseInt(process.env.DB_PORT || '3306')
+  });
+
+  // 새 자산들의 연도 분포 확인
+  const [years] = await connection.query('SELECT DISTINCT purchase_date FROM asset_core WHERE id LIKE "PC_20260615_%"');
+  console.log('New assets years:', years.map(y => y.purchase_date));
+
+  // 기존 자산 코드 패턴 확인
+  const [existing] = await connection.query('SELECT asset_code FROM asset_core WHERE asset_code LIKE "PC-%" LIMIT 5');
+  console.log('Existing code sample:', existing);
+
+  await connection.end();
+}
+
+analyzeCodes().catch(console.error);