Fix encryption not working after restarting

src/backend/utils/system-crypto.ts

@@ -260,14 +260,15 @@ class SystemCrypto {
    * Update .env file with new environment variable
    */
   private async updateEnvFile(key: string, value: string): Promise<void> {
-    // Use persistent config directory if available (Docker), otherwise use current directory
-    const configDir = process.env.NODE_ENV === 'production' &&
-                     await fs.access('/app/config').then(() => true).catch(() => false)
-                     ? '/app/config'
-                     : process.cwd();
-    const envPath = path.join(configDir, ".env");
+    // Use data directory for .env file (where database is stored)
+    // This keeps keys and data together in one volume
+    const dataDir = process.env.DATA_DIR || "./db/data";
+    const envPath = path.join(dataDir, ".env");
 
     try {
+      // Ensure data directory exists
+      await fs.mkdir(dataDir, { recursive: true });
+
       let envContent = "";
 
       // Read existing .env file if it exists