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

scratch/debug_public.cjs

@@ -0,0 +1,25 @@
+const mysql = require('mysql2/promise');
+require('dotenv').config();
+
+async function debugPublic() {
+  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')
+  });
+
+  const [rows] = await connection.query(`
+    SELECT user_current, emp_no, COUNT(*) as count 
+    FROM asset_core 
+    WHERE id LIKE "PC_20260615_%"
+    GROUP BY user_current, emp_no
+    HAVING emp_no IS NULL OR emp_no = '' OR user_current LIKE '%공용%' OR user_current = ''
+  `);
+
+  console.table(rows);
+  await connection.end();
+}
+
+debugPublic().catch(console.error);