✨ [shared] Replace Neovim with Helix

Moved Helix editor to shared.
Removed Nixvim flake and it's config

shared/home-manager/development/helix.nix

@@ -0,0 +1,33 @@
+{ pkgs, theme, ... }:
+
+{
+  catppuccin.helix = {
+    enable = true;
+    flavor = theme.flavor;
+  };
+
+  programs = {
+    fish.shellAliases.edit = "hx";
+    helix = {
+      enable = true;
+      defaultEditor = true;
+      settings = {
+        editor = {
+          cursor-shape = {
+            normal = "block";
+            insert = "bar";
+            select = "underline";
+          };
+          lsp.display-messages = true;
+        };
+      };
+      languages.language = [
+        {
+          name = "nix";
+          auto-format = true;
+          formatter.command = "${pkgs.nixfmt-rfc-style}/bin/nixfmt";
+        }
+      ];
+    };
+  };
+}