Update VS Code settings

- "eslint.validate": [ "javascript" ] is no longer needed
    (Modern versions of the ESLint VS Code extensions
    automatically validate JavaScript files by default.)
- Configure editor to use tabs instead of spaces per ESLint rules
- Switch to VS Code's built-in HTML formatter
- Add EJS file associations for proper syntax highlighting
- Add recommended extensions for development workflow

.vscode/settings.json

@@ -17,7 +17,4 @@
 	"editor.codeActionsOnSave": {
 		"source.fixAll.eslint": "explicit"
 	},
-	"eslint.validate": [
-		"javascript"
-	],
-}
+}