refactor: testing

Redid testing structure, added tests and changed some tests.

ref: N25B-301

test/unit/core/test_config.py

@@ -0,0 +1,14 @@
+"""Test if settings load correctly and environment variables override defaults."""
+
+from control_backend.core.config import Settings
+
+
+def test_default_settings():
+    settings = Settings()
+    assert settings.app_title == "PepperPlus"
+
+
+def test_env_override(monkeypatch):
+    monkeypatch.setenv("APP_TITLE", "TestPepper")
+    settings = Settings()
+    assert settings.app_title == "TestPepper"