cleaned up backend to use classes and yaml files

backend/src/structs/landmarks.py

@@ -8,7 +8,7 @@ class Landmark(BaseModel) :
     
     # Properties of the landmark
     name : str
-    type: Literal['sightseeing', 'nature', 'shopping']
+    type: Literal['sightseeing', 'nature', 'shopping', 'start', 'finish']
     location : tuple
     osm_type : str
     osm_id : int
@@ -22,8 +22,8 @@ class Landmark(BaseModel) :
     uuid: str = Field(default_factory=uuid4)                    # TODO implement this ASAP
     
     # Additional properties depending on specific tour
-    must_do : bool
-    must_avoid : bool
+    must_do : Optional[bool] = False
+    must_avoid : Optional[bool] = False
     is_secondary : Optional[bool] = False                       # TODO future   
     
     time_to_reach_next : Optional[int] = 0                      # TODO fix this in existing code

backend/src/structs/preferences.py

@@ -3,7 +3,7 @@ from typing import Optional, Literal
 
 class Preference(BaseModel) :
     name: str
-    type: Literal['sightseeing', 'nature', 'shopping']
+    type: Literal['sightseeing', 'nature', 'shopping', 'start', 'finish']
     score: int          # score could be from 1 to 5
 
 # Input for optimization