Unify redirection middleware.

[samuel-williams-shopify]

Summary

• replace the per-redirection middleware classes with one configurable Utopia::Redirection middleware
• retain Utopia::Redirection::Errors as a separate response-phase middleware for internal error requests
• evaluate client-facing request rules in declaration order
• update generated configuration, guides, and fixtures for the split API

Testing

• focused middleware tests: 33 examples, 81 assertions
• redirection tests: 12 examples, 29 assertions
• documentation coverage: 478/478 definitions
• RuboCop: changed Ruby files, no offenses
• full in-repository run: 321 examples passed; four command-generation tests remain blocked locally by stale native extensions in vendor/bundle (date_core.bundle Ruby ABI mismatch)

The external utopia-project consumer has been migrated in socketry/utopia-project#16.