Fix NFO folder naming to include year

- Add Serie.ensure_folder_with_year() method to ensure folder names include year
- Update all NFO API endpoints to call ensure_folder_with_year() before operations
- Folder format is now 'Name (Year)' when year is available
- Add comprehensive tests for ensure_folder_with_year() method
- All 5 tests passing

src/core/entities/series.py

@@ -1,4 +1,5 @@
 import json
+import logging
 import os
 import warnings
 from pathlib import Path
@@ -6,6 +7,8 @@ from typing import Optional
 
 from src.server.utils.filesystem import sanitize_folder_name
 
+logger = logging.getLogger(__name__)
+
 
 class Serie:
     """
@@ -290,6 +293,36 @@ class Serie:
             # Fallback to key if name cannot be sanitized
             return sanitize_folder_name(self._key)
 
+    def ensure_folder_with_year(self) -> str:
+        """Ensure folder name includes year if available.
+        
+        If the serie has a year and the current folder name doesn't include it,
+        updates the folder name to include the year in format "Name (Year)".
+        
+        This method should be called before creating folders or NFO files to
+        ensure consistent naming across the application.
+        
+        Returns:
+            str: The folder name (updated if needed)
+            
+        Example:
+            >>> serie = Serie("perfect-blue", "Perfect Blue", ..., folder="Perfect Blue", year=1997)
+            >>> serie.ensure_folder_with_year()
+            'Perfect Blue (1997)'
+            >>> serie.folder  # folder property is updated
+            'Perfect Blue (1997)'
+        """
+        if self._year:
+            # Check if folder already has year format
+            year_pattern = f"({self._year})"
+            if year_pattern not in self._folder:
+                # Update folder to include year
+                self._folder = self.sanitized_folder
+                logger.info(
+                    f"Updated folder name for '{self._key}' to include year: {self._folder}"
+                )
+        return self._folder
+
     def to_dict(self):
         """Convert Serie object to dictionary for JSON serialization."""
         return {