fix: add SQLite busy_timeout and fix regex escape warning

Set PRAGMA busy_timeout=30000 on SQLite connections to prevent
"database is locked" errors under concurrent access. Fix invalid
escape sequence in email regex by using raw string.

make_post_sell/models/__init__.py

@@ -1,4 +1,4 @@
-from sqlalchemy import engine_from_config
+from sqlalchemy import engine_from_config, event
 from sqlalchemy.orm import sessionmaker
 from sqlalchemy.orm import configure_mappers
 import zope.sqlalchemy
@@ -38,7 +38,16 @@ configure_mappers()
 
 
 def get_engine(settings, prefix="sqlalchemy."):
-    return engine_from_config(settings, prefix)
+    engine = engine_from_config(settings, prefix)
+    if engine.url.get_backend_name() == "sqlite":
+
+        @event.listens_for(engine, "connect")
+        def set_sqlite_pragma(dbapi_conn, connection_record):
+            cursor = dbapi_conn.cursor()
+            cursor.execute("PRAGMA busy_timeout = 30000")
+            cursor.close()
+
+    return engine
 
 
 def get_session_factory(engine):

make_post_sell/views/authentication.py

@@ -39,7 +39,7 @@ def join_or_log_in(request):
     OTP (one-time-password) tokens to email addresses to verify both the email
     address & to authenticate the device displaying the challenge input field.
     """
-    _email_regex = re.compile("^[^@]+@[^@]+\.[^.@]+$")
+    _email_regex = re.compile(r"^[^@]+@[^@]+\.[^.@]+$")
     raw_otp = request.params.get("raw-otp", "")
     email = request.params.get("email", "")