Refactor tests to remove redundancy and improve structure

- Remove redundant 'mixed input patterns' test from sanitizer.test.ts
- Consolidate integration tests into 2 focused real-world scenarios
- Add HTML comment stripping to sanitizeContent function
- Update test expectations to match sanitization behavior
- Maintain full coverage with fewer, more focused tests

src/github/utils/sanitizer.ts

@@ -52,6 +52,7 @@ export function normalizeHtmlEntities(content: string): string {
 }
 
 export function sanitizeContent(content: string): string {
+  content = stripHtmlComments(content);
   content = stripInvisibleCharacters(content);
   content = stripMarkdownImageAltText(content);
   content = stripMarkdownLinkTitles(content);