Add django-simple-csp derivation and include it in the Python environment

flake.nix

@@ -19,6 +19,31 @@
           sha256 = "sha256-R4OwQdSJu9+EAlkhYOEe2ZOrS9oOA1ifg/iY6uzYSpE=";
         };
 
+        # Create django-simple-csp derivation
+        django-simple-csp = pkgs.python3.pkgs.buildPythonPackage rec {
+          pname = "django-simple-csp";
+          version = "0.4.dev1";
+          
+          src = pkgs.fetchFromGitHub {
+            owner = "fsinfuhh";
+            repo = "django-simple-csp";
+            rev = "207afedec1bf28af5de070da919061474b1f6a21";
+            sha256 = "sha256-1rvdplHPjVZ6li831/sQT+lL4rE8ME1eLfeSd0EKHb4=";
+          };
+          
+          propagatedBuildInputs = with pkgs.python3.pkgs; [
+            django
+          ];
+          
+          doCheck = false; # Skip tests during build
+          
+          meta = with pkgs.lib; {
+            description = "Django Content Security Policy support";
+            homepage = "https://github.com/fsinfuhh/django-simple-csp";
+            license = licenses.mit;
+          };
+        };
+
         # Create settings_local.py for production
         settingsLocal = pkgs.writeText "settings_local.py" ''
           import os
@@ -69,6 +94,7 @@
         pythonEnv = pkgs.python3.withPackages (ps: with ps; [
           # Core Django dependencies
           django
+          django-simple-csp
           
           # Calendar and date handling
           caldav
@@ -144,7 +170,6 @@
             mkdir -p $out/lib/python3.12/site-packages
             
             ${pythonEnv}/bin/pip install --target $out/lib/python3.12/site-packages \
-              django-simple-csp==0.4.dev1 \
               django-markdownify==0.9.5 \
               django-pipeline==3.1.0 \
               django-friendly-tag-loader==1.3.1 \