cleanup path handling for easier dockerization

backend/src/constants.py

@@ -0,0 +1,9 @@
+from pathlib import Path
+
+
+PARAMETERS_DIR = Path('src/parameters')
+AMENITY_SELECTORS_PATH = PARAMETERS_DIR / 'amenity_selectors.yaml'
+LANDMARK_PARAMETERS_PATH = PARAMETERS_DIR / 'landmark_parameters.yaml'
+OPTIMIZER_PARAMETERS_PATH = PARAMETERS_DIR / 'optimizer_parameters.yaml'
+
+OSM_CACHE_DIR = Path('cache')