Fix template metadata and naming

- Changed omnix template name from "default" to "vanilla" for clarity
- Updated flake descriptions to describe project type, not template repo
- Added {{package-name}} variable to vanilla/package.json for substitution

Ensures initialized projects have correct metadata and users see "vanilla"
and "nextjs" as template options during initialization.

nix/modules/template.nix

@@ -15,7 +15,7 @@ in {
     };
 
     om.templates = {
-      default = {
+      vanilla = {
         template = templates.default;
         params = [
           {

templates/nextjs/flake.nix

@@ -1,5 +1,5 @@
 {
-  description = "Nix templates for JavaScript projects, powered by Bun";
+  description = "Next.js TypeScript project with App Router, Bun, and Nix";
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-24.11";

templates/vanilla/flake.nix

@@ -1,5 +1,5 @@
 {
-  description = "Nix templates for JavaScript projects, powered by Bun";
+  description = "Vanilla JavaScript project with Vite, Bun, and Nix";
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-24.11";

templates/vanilla/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "javascript-template",
+  "name": "{{package-name}}",
   "version": "1.0.0",
   "type": "module",
   "scripts": {