Add website scraper for importing existing PWB sites as seed packs

Creates a rake task to scrape content from existing PropertyWebBuilder
websites and generate seed pack YAML files for provisioning new sites.
Scraped packs are stored in git-ignored db/seeds/site_import_packs/.

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

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

Author: etewiah

.gitignore

@@ -129,3 +129,7 @@ lighthouse-reports/
 # Production test artifacts
 test-results-production/
 playwright-report-production/
+
+# Scraped/imported site packs (generated by website scraper)
+db/seeds/site_import_packs/
+!db/seeds/site_import_packs/.keep