multi(core): Various fixes to the Settings system

[dazuma]

fix(core): Block certain reserved names from being used as Settings field names
fix(core): Fixed Settings#load_data! when subclassing another settings class
fix(core): Reject non-String values in Settings regexp type spec
fix(core): Settings guards against unknown classes when loading YAML on older Ruby versions
fix(core): Settings guards against ILLEGAL_VALUE being passed to range.member?
fix(core): Settings does a better job choosing exact-match values when using a union type
fix(core): Settings reject non-numeric strings in Integer and Float converters
fix(core): Settings propagates nested group errors in Settings#load_data!

[Copilot]

Pull request overview

This PR improves the robustness and safety of Toys::Settings type validation and data loading, adding guards for edge cases (e.g., inherited fields, YAML loading, and stricter conversions) and expanding test coverage to lock in the behavior.

Changes:

• Add reserved settings field name blocking and improve type matching/conversion behavior (ranges, regexps, unions, numeric parsing).
• Fix settings field inheritance for subclasses and propagate nested-group loading errors correctly (including raise_on_failure behavior).
• Switch YAML loading to Psych.safe_load (disallowing arbitrary Ruby object deserialization) while permitting symbols.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
toys-core/lib/toys/settings.rb	Core fixes: reserved names, safer YAML loading, improved converters/type matching, inherited fields, and nested error propagation.
toys-core/test/test_settings.rb	Adds regression tests for reserved names, subclass field inheritance, stricter conversions, union prioritization, ranges, YAML safety, and nested error propagation.

Comments suppressed due to low confidence (1)

toys-core/lib/toys/settings.rb:910

• interpret_name only checks public_instance_methods(false) for duplicates, so with the new inherited fields behavior a subclass can re-declare a field name that already exists in the superclass without raising, silently overwriting the inherited field definition and accessor methods. Consider also checking fields.key?(name.to_sym) and/or using public_instance_methods (including inherited) so redefinitions are rejected consistently across inheritance.

      def interpret_name(name)
        name = name.to_s
        if name !~ /^[a-zA-Z]\w*$/ || RESERVED_FIELD_NAMES.include?(name)
          raise ::ArgumentError, "Illegal settings field name: #{name}"
        end
        existing = public_instance_methods(false)
        if existing.include?(name.to_sym) || existing.include?(:"#{name}=") ||
           existing.include?(:"#{name}_set?") || existing.include?(:"#{name}_unset!")
          raise ::ArgumentError, "Settings field already exists: #{name}"

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