Refactor imports and improve logging in multiple modules; streamline type hints and remove redundant code

src/data_manager.py

@@ -1,7 +1,6 @@
-import os
 import csv
 import logging
-from typing import List, Union
+import os
 
 import pandas as pd
 
@@ -36,13 +35,8 @@ class DataManager:
 
     def load_data(self) -> pd.DataFrame:
         """Load data from CSV file."""
-        if (
-            not os.path.exists(self.filename)
-            or os.path.getsize(self.filename) == 0
-        ):
-            self.logger.warning(
-                "CSV file is empty or doesn't exist. No data to load."
-            )
+        if not os.path.exists(self.filename) or os.path.getsize(self.filename) == 0:
+            self.logger.warning("CSV file is empty or doesn't exist. No data to load.")
             return pd.DataFrame()
 
         try:
@@ -69,7 +63,7 @@ class DataManager:
             self.logger.error(f"Error loading data: {str(e)}")
             return pd.DataFrame()
 
-    def add_entry(self, entry_data: List[Union[str, int]]) -> bool:
+    def add_entry(self, entry_data: list[str | int]) -> bool:
         """Add a new entry to the CSV file."""
         try:
             with open(self.filename, mode="a", newline="") as file:
@@ -80,7 +74,7 @@ class DataManager:
             self.logger.error(f"Error adding entry: {str(e)}")
             return False
 
-    def update_entry(self, date: str, values: List[Union[str, int]]) -> bool:
+    def update_entry(self, date: str, values: list[str | int]) -> bool:
         """Update an existing entry identified by date."""
         try:
             df: pd.DataFrame = self.load_data()