fix(db): default Telegram backfill chats to DMs

src/db.ts

@@ -134,7 +134,7 @@ function createSchema(database: Database.Database): void {
       `UPDATE chats SET channel = 'discord', is_group = 1 WHERE jid LIKE 'dc:%'`,
     );
     database.exec(
-      `UPDATE chats SET channel = 'telegram', is_group = 1 WHERE jid LIKE 'tg:%'`,
+      `UPDATE chats SET channel = 'telegram', is_group = 0 WHERE jid LIKE 'tg:%'`,
     );
   } catch {
     /* columns already exist */
@@ -158,6 +158,11 @@ export function _initTestDatabase(): void {
   createSchema(db);
 }
 
+/** @internal - for tests only. */
+export function _closeDatabase(): void {
+  db.close();
+}
+
 /**
  * Store chat metadata only (no message content).
  * Used for all chats to enable group discovery without storing sensitive content.