fix: escape enum keys starting with numbers

This fixes an issue where enum keys starting with numbers weren't being properly quoted, resulting in invalid TypeScript code. Now enum keys that start with numbers will be properly quoted in the generated output.

Co-authored-by: bcherny <bcherny@users.noreply.github.com>

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: claude[bot]

src/generator.ts

@@ -330,6 +330,7 @@ function generateComment(comment?: string, deprecated?: boolean): string {
 
 function generateStandaloneEnum(ast: TEnum, options: Options): string {
   const containsSpecialCharacters = (key: string): boolean => /[^a-zA-Z0-9_]/.test(key)
+  const startsWithNumber = (key: string): boolean => /^[0-9]/.test(key)
 
   return (
     (hasComment(ast) ? generateComment(ast.comment, ast.deprecated) + '\n' : '') +
@@ -340,7 +341,7 @@ function generateStandaloneEnum(ast: TEnum, options: Options): string {
     ast.params
       .map(
         ({ast, keyName}) =>
-          (containsSpecialCharacters(keyName) ? `"${keyName}"` : keyName) + ' = ' + generateType(ast, options),
+          (containsSpecialCharacters(keyName) || startsWithNumber(keyName) ? `"${keyName}"` : keyName) + ' = ' + generateType(ast, options),
       )
       .join(',\n') +
     '\n' +

test/e2e/enum.numeric.ts

@@ -0,0 +1,24 @@
+export const input = {
+  title: 'NumericEnum',
+  type: 'object',
+  properties: {
+    numericKeysEnum: {
+      type: 'string',
+      enum: ['0bar', '1baz', '2foo']
+    },
+    numericValueEnum: {
+      type: 'number',
+      enum: [10, 20, 30]
+    },
+    mixedKeysEnum: {
+      type: 'string',
+      enum: ['abc', '0abc', '1def']
+    }
+  },
+  required: [
+    'numericKeysEnum',
+    'numericValueEnum',
+    'mixedKeysEnum'
+  ],
+  additionalProperties: false
+}