refactor: Centralize database session management in a shared dependency module

routes/distributions.py

@@ -1,25 +1,19 @@
+from typing import Dict, List
+
 from fastapi import APIRouter, Depends
-from sqlalchemy.orm import Session
-from typing import List
 from pydantic import BaseModel, ConfigDict
-from config.database import SessionLocal
+from sqlalchemy.orm import Session
+
 from models.distribution import Distribution
+from routes.dependencies import get_db
 
 router = APIRouter(prefix="/api/distributions", tags=["Distributions"])
 
 
-def get_db():
-    db = SessionLocal()
-    try:
-        yield db
-    finally:
-        db.close()
-
-
 class DistributionCreate(BaseModel):
     name: str
     distribution_type: str
-    parameters: dict
+    parameters: Dict[str, float | int]
 
 
 class DistributionRead(DistributionCreate):