Analyse: Tageswerte nach 25 Monaten löschen, secure_delete, CSV-Export

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

analytics/src/db.js

@@ -55,6 +55,7 @@ CREATE TABLE IF NOT EXISTS agg_state (
 export function openDb(path) {
   const db = new DatabaseSync(path);
   if (path !== ':memory:') db.exec('PRAGMA journal_mode = WAL');
+  db.exec('PRAGMA secure_delete = ON');
   db.exec(SCHEMA);
   return db;
 }