refactor: restructure core→server, split large entity files into database module

- Move src/core/ → src/server/
- Split SerieList.py (531 lines) and series.py (414 lines) into src/server/database/
- Add database/models.py for SQLAlchemy models
- Update all test imports to reflect new structure
- Remove deprecated test files (test_serie_class.py, test_serie_folder_with_year.py)

src/server/interfaces/providers.py

@@ -0,0 +1,11 @@
+
+from ..providers.streaming.Provider import Provider
+from ..providers.streaming.voe import VOE
+
+class Providers:
+
+    def __init__(self):
+        self.dict = {"VOE": VOE()}
+
+    def GetProvider(self, key: str) -> Provider:
+        return self.dict[key]