Refactor test configurations and enhance testing framework

- Replace TempConfig with DummyConfig across tests for consistency
- Introduce unit tests workflow configuration
- Add pytest configuration for standardized test discovery
- Implement comprehensive tests for config loading and downloader behavior
- Clean up unused temp_config.py and related references

tests/test_manager_connection_warning.py

@@ -0,0 +1,26 @@
+import logging
+from tests.dummy_config import DummyConfig
+from ytplaylist.manager import PlaylistManager
+
+
+def test_manager_warns_and_sleeps(monkeypatch, caplog):
+    # Avoid actually sleeping during the test
+    slept = {"called": False}
+
+    def fake_sleep(sec):
+        slept["called"] = True
+
+    # monkeypatch the sleep used inside the manager module
+    monkeypatch.setattr("ytplaylist.manager.time.sleep", fake_sleep)
+
+    caplog.set_level(logging.WARNING)
+    cfg = DummyConfig()
+    cfg.max_parallel_downloads = 11
+    cfg.aria2c_connections = 10
+    cfg.playlists = []
+
+    m = PlaylistManager(cfg, debug=False)
+    m.run()
+
+    assert slept["called"] is True
+    assert any("may overload your network" in rec.getMessage() for rec in caplog.records)