fix(schema): revert 200->None replacement feature

go-sqlite3 used in server can not process NULLs

addon.py

@@ -18,7 +18,7 @@ with db as conn:
             id integer primary key,
             method text not null default "GET",
             url text not null,
-            code integer default null
+            code integer not null default 200
         );
     ''')
 
@@ -35,7 +35,7 @@ def response(flow: HTTPFlow) -> None:
         code = flow.response.status_code
         cur = conn.execute(
             'insert into data (method, url, code) values (?, ?, ?) returning id',
-            (req.method, url, code if code != 200 else None),
+            (req.method, url, code),
         )
         uid = cur.fetchone()[0]
     path = os.path.join(storage, f'{uid}')