refactor: migrate Font Awesome to npm package

- Remove Font Awesome files from public/assets and update .gitignore
- Switch from CDN to local npm package for Font Awesome
- Update BaseLayout.astro to use Font Awesome from node_modules
- Add specific gitignore patterns for vendor files
- Keep public/assets directory structure for future custom assets

This change improves the project by:
1. Using proper dependency management through npm
2. Reducing external dependencies on CDN
3. Maintaining cleaner source control
4. Following best practices for vendor file management

.gitignore

@@ -7,6 +7,10 @@ dist/
 # dependencies
 node_modules/
 
+# vendor files
+public/assets/fontawesome/
+node_modules/@fortawesome/
+
 # logs
 npm-debug.log*
 yarn-debug.log*
@@ -17,6 +21,9 @@ pnpm-debug.log*
 .env
 .env.production
 
+# DevContainer environment files
+.devcontainer/.env
+
 # macOS-specific files
 .DS_Store
 
@@ -28,5 +35,3 @@ pnpm-debug.log*
 # Test coverage
 coverage/
 
-# DevContainer environment files
-.devcontainer/.env