Fix scroll position test by correctly extracting hash from href

The href attributes in REX links contain the full path (e.g., "test-page-for-generic-styles#main-content")
not just the hash (e.g., "#main-content"). This was causing the selector to be constructed incorrectly
as "#test-page-for-generic-styles#main-content" which is an invalid compound ID selector.

Changed the targetId extraction from:
  href?.replace(/^#/, '')
to:
  href?.match(/#(.+)$/)?[1]

This properly extracts only the part after the # symbol, resulting in correct selectors like "#main-content".

Addresses Review #43

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: OpenStaxClaude

src/app/content/components/Content.browserspec.tsx

@@ -153,7 +153,10 @@ describe('Content', () => {
         for (const link of links) {
           // Get the href before clicking to know what element we're scrolling to
           const href = await page.evaluate((el) => el.getAttribute('href'), link);
-          const targetId = href?.replace(/^#/, '') || '';
+          // Extract just the hash part (after the # symbol) from href
+          // href might be "#main-content" or "page-slug#main-content"
+          const hashMatch = href?.match(/#(.+)$/);
+          const targetId = hashMatch ? hashMatch[1] : '';
 
           /* eslint-disable no-console */
           console.info('*** Clicking link with href:', href, 'targetId:', targetId);