remove unused shell templates and fix nix-shell prompt

home.nix

@@ -87,8 +87,9 @@
   programs.starship = {
     enable = true;
     enableZshIntegration = true;
+    enableBashIntegration = true;
     settings = {
-      format = "$hostname$directory$git_branch$git_status$direnv$line_break$character";
+      format = "$hostname$directory$git_branch$git_status$direnv$nix_shell$line_break$character";
       right_format = "$time";
 
       hostname = {
@@ -139,6 +140,14 @@
         unloaded_msg = "not loaded";
       };
 
+      nix_shell = {
+        format = "[$symbol$state]($style) ";
+        symbol = "❄ ";
+        style = "bold #cd0a00";
+        impure_msg = "nix";
+        pure_msg = "nix-pure";
+      };
+
       character = {
         success_symbol = "[❯](bold green)";
         error_symbol = "[❯](bold red)";
@@ -177,7 +186,7 @@
 
   home.sessionVariables = {
     _ZO_FZF_OPTS = "--preview 'eza --tree --level=2 --color=always {2..}' --preview-window=right:40%";
-    NIX_BUILD_SHELL = "zsh";
+    NIX_BUILD_SHELL = "bash";
     NIXOS_OZONE_WL = "1";
   };