feat: enhance error handling and configuration validation

- Added a global exception handler to log unhandled exceptions and return a generic 500 JSON response without exposing details to the client.
- Updated the configuration to validate the `DATABASE_URL` format, ensuring it starts with `sqlite://` or `postgresql://`, and log warnings for invalid formats.
- Introduced safe parsing for numeric environment variables (`HTTP_PORT`, `INIT_DATA_MAX_AGE_SECONDS`) with defaults on invalid values, including logging warnings for out-of-range values.
- Enhanced the duty schedule parser to enforce limits on the number of schedule rows and the length of full names and duty strings, raising appropriate errors when exceeded.
- Updated internationalization messages to include generic error responses for import failures and parsing issues, improving user experience.
- Added unit tests to verify the new error handling and configuration validation behaviors.

tests/test_run.py

@@ -24,14 +24,23 @@ def test_main_builds_app_and_starts_thread():
     mock_scope.return_value.__exit__.return_value = None
 
     with patch("duty_teller.run.require_bot_token"):
-        with patch("duty_teller.run.ApplicationBuilder", return_value=mock_builder):
-            with patch("duty_teller.run.register_handlers") as mock_register:
-                with patch("duty_teller.run.threading.Thread") as mock_thread_class:
-                    with patch("duty_teller.db.session.session_scope", mock_scope):
-                        mock_thread = MagicMock()
-                        mock_thread_class.return_value = mock_thread
-                        with pytest.raises(KeyboardInterrupt):
-                            main()
+        with patch("duty_teller.run.config") as mock_cfg:
+            mock_cfg.MINI_APP_SKIP_AUTH = False
+            mock_cfg.HTTP_HOST = "127.0.0.1"
+            mock_cfg.HTTP_PORT = 8080
+            with patch("duty_teller.run.ApplicationBuilder", return_value=mock_builder):
+                with patch("duty_teller.run.register_handlers") as mock_register:
+                    with patch("duty_teller.run.threading.Thread") as mock_thread_class:
+                        with patch(
+                            "duty_teller.run._wait_for_http_ready", return_value=True
+                        ):
+                            with patch(
+                                "duty_teller.db.session.session_scope", mock_scope
+                            ):
+                                mock_thread = MagicMock()
+                                mock_thread_class.return_value = mock_thread
+                                with pytest.raises(KeyboardInterrupt):
+                                    main()
     mock_register.assert_called_once_with(mock_app)
     mock_builder.token.assert_called_once()
     mock_thread.start.assert_called_once()