feat: Add flake and ragenix package generation and dev environment

secrets/secrets.nix

@@ -0,0 +1,14 @@
+# Public keys for secret encryption
+# Add your age or SSH public keys here
+{
+  publicKeys = [
+    # Example age public key:
+    # "age1qyqszqgpqyqszqgpqyqszqgpqyqszqgpqyqszqgpqyqszqgpqyqs3ekg8p"
+    
+    # Example SSH public key (ed25519):
+    # "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAI... user@host"
+    
+    # Add your keys below:
+    # TODO: Add your age or SSH public keys
+  ];
+}