Add core inspector, CLI, and formatter

- Inspector extracts callbacks and validators from any AR model,
  resolves source locations, and filters Rails internals
- CLI: `whetrails inspect <ModelName>` boots Rails and renders chain
- Formatter produces clean lifecycle-ordered terminal output
- Order model added as development fixture

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

exe/whetrails

@@ -0,0 +1,6 @@
+#!/usr/bin/env ruby
+
+$LOAD_PATH.unshift(File.expand_path("../lib", __dir__))
+require "whetrails/cli"
+
+Whetrails::CLI.run(ARGV)