Fix Fleetbase blog Ghost feed lookup

[roncodes]

Summary

• switch the Fleetbase blog lookup from the old Webflow RSS URL to the public Ghost RSS feed
• normalize Ghost post links to canonical fleetbase.io/blog URLs for the console widget
• add a reusable FleetbaseBlog parser with coverage for RSS parsing, link rewriting, malformed feeds, and limits

Root cause

The console widget still called the core-api lookup endpoint, but that endpoint fetched https://www.fleetbase.io/post/rss.xml, which now returns 404 after the blog moved to Ghost. The widget then had no posts to render.