Add 3x-ui user sync via panel API (login or Bearer token).

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

db/connection.py

@@ -78,5 +78,15 @@ def init_schema():
                 if stmt:
                     cur.execute(stmt)
         conn.commit()
+    # Soft migrations for existing databases
+    with pool.connection() as conn:
+        with conn.cursor() as cur:
+            cur.execute(
+                "ALTER TABLE users ADD COLUMN IF NOT EXISTS xui_email TEXT"
+            )
+            cur.execute(
+                "CREATE INDEX IF NOT EXISTS idx_users_xui_email ON users(xui_email)"
+            )
+        conn.commit()
     _schema_ready = True
     logger.info('PostgreSQL schema ready')