Reading `.htaccess` mod_rewrite Rules: A Real `RewriteBase` Trap From a Subdomain Migration

A WordPress URL like https://example.com/blog/some-post-title/ looks clean, but there's no directory or file on the server that actually matches that path. Behind the scenes, Apache's mod_rewrite module intercepts the request and silently forwards it to index.php. The rules that make this happen live in .htaccess, and when a WordPress site...