Fix Postgres startup: add xui_email before creating its index.

Co-authored-by: Cursor <cursoragent@cursor.com>

db/schema.sql

@@ -35,8 +35,6 @@ CREATE TABLE IF NOT EXISTS users (
     share_password_hash TEXT
 );
 
-CREATE INDEX IF NOT EXISTS idx_users_xui_email ON users(xui_email);
-
 CREATE TABLE IF NOT EXISTS user_connections (
     id UUID PRIMARY KEY,
     user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,