Fix enum column prefix/suffix

Add Sample Rails app

Added some documents.

MarshalLoader#read_raw raised Errno::ENOENT when the dump file did not
exist, which prevented bootstrapping a dataset before any dump was
produced. Align the behavior with QueryLoader's empty-table fallback so
loading a missing table yields an empty record set instead.

Also realign the inner-block indentation in queryable.rb so newer
RuboCop (Layout/IndentationWidth) stops flagging it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Newer RuboCop releases activated Style/OneClassPerFile by default,
which flags two intentional patterns in this codebase:

- The ActiveRecord::Associations::Preloader::Association reopen in
  lib/simple_master.rb, which is a monkey-patch and not a new class.
- STI subclass families colocated in a single model file in the
  rails_sample.

Both patterns are deliberate, so disable the cop project-wide.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Patch release covering the MarshalLoader missing-file fix. No public
API changes; behavior change is limited to gracefully handling a
previously-unhandled error path (missing dump file -> empty record
set), matching QueryLoader's existing fallback.

Adds CHANGELOG.md (Keep a Changelog format) starting from v1.0.0 so
future entries have a home.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Treat missing marshal files as empty record sets