Previously, the method created a SerieList instance which only loads
from database, not from data files. Now reads data files directly
and parses JSON to create AnimeSeries objects.
Also added _load_data_file helper function and fixed logger.warning
calls to use proper format strings instead of keyword arguments.
Updated unit tests to use real temp directories instead of mocks.
- 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)
