Enhance development environment and improve main.py functionality

- Added `black` to the development environment in flake.nix for code formatting.
- Updated shell hook to include instructions for using `black`.
- Refactored `main.py` to improve code organization and readability, including reordering imports and simplifying list comprehensions.
- Enhanced album processing functions for better clarity and efficiency.
- Improved error handling and output formatting for better user experience.

flake.nix

@@ -17,10 +17,14 @@
       in
       {
         devShells.default = pkgs.mkShell {
-          buildInputs = [ pythonEnv ];
+          buildInputs = [ 
+            pythonEnv
+            pkgs.black
+          ];
           shellHook = ''
             echo "Python environment ready!"
             echo "Run: python main.py"
+            echo "Format code with: black main.py"
           '';
         };