Fix sessions table: add impersonator_id column

db/schema.sql

@@ -66,6 +66,7 @@ CREATE TABLE IF NOT EXISTS sessions (
   user_agent      TEXT,
   data            TEXT,
   expires_at      TEXT NOT NULL,
+  impersonator_id INTEGER DEFAULT NULL,
   created_at      TEXT DEFAULT (datetime('now')),
   FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
 );