Add Blueprinter integration for Rage::OpenAPI

[sanithrshetty15]

Summary

This PR adds static analysis support for the Blueprinter serializer
in Rage::OpenAPI, following the same pattern as the existing Alba integration.

Problem

Rage::OpenAPI currently only supports Alba serializers for auto-generating
OpenAPI schemas. Blueprinter is one of the most widely used Ruby serializers
but has no support — leaving those developers with no OpenAPI coverage.

Solution

A new parser Rage::OpenAPI::Parsers::Ext::Blueprinter that:

• Parses Blueprinter class definitions using Prism AST (no runtime loading)
• Supports field and identifier declarations
• Supports association with nested blueprint resolution
• Supports view blocks including named views like :extended
• Supports collection wrapping via [BlueprintName] syntax
• Includes circular reference protection via a parsing stack

Tests

10 RSpec tests added covering all major features:

• Single and multiple fields
• Identifier detection
• Associations with and without blueprints
• Default view isolation
• Extended view with inherited fields
• Collection wrapping
• known_definition? detection

Checklist

• Tests pass (1729 examples, 0 failures)
• Follows existing Alba integration pattern
• No runtime loading — pure static AST analysis