feat: Better structure, add tests

backend/tests/test_config.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+
+from config import AppSettings, as_public_dict
+
+
+def test_app_settings_load_from_toml_and_masks_api_key(tmp_path) -> None:
+    config_path = tmp_path / "config.toml"
+    config_path.write_text(
+        """
+[llm]
+model = "test-model"
+api_key = "super-secret"
+
+[game]
+hard_mode_rotation_interval = 3
+blocked_response_text = "blocked"
+password_words = [
+  "w01", "w02", "w03", "w04", "w05",
+  "w06", "w07", "w08", "w09", "w10",
+  "w11", "w12", "w13", "w14", "w15",
+  "w16", "w17", "w18", "w19", "w20",
+]
+""".strip(),
+        encoding="utf-8",
+    )
+
+    settings = AppSettings.from_toml(config_path)
+    public_data = as_public_dict(settings)
+
+    assert settings.llm.model == "test-model"
+    assert settings.game.hard_mode_rotation_interval == 3
+    assert public_data["llm"]["api_key"] == "***"