Query command for database queries and more

This week in Rails covers several new features and fixes. The headline addition is the `rails query` command, a read-only database query tool that accepts ActiveRecord expressions and returns structured JSON output with metadata including SQL, row count, and query time. Subcommands like `query schema`, `query models`, and `query explain` are also included. Other changes include appending `charset=utf-8` to Content-Type headers for static CSS and HTML files, adding an offline fallback page to the PWA scaffold, a rewrite of the Layouts and Rendering guide, a performance improvement using hash lookup for exact-match regexp filters in ParameterFilter, and a clarification of Active Storage security around signed URLs.