[GH-7682] Add ExpressionDeclaration, AssignmentsProvider, and new call-site API to eliminate raw AST usage in existing lint rules

[Bastian (bkoell)]

What changed and why

Checklist

• Tests are added or updated for the changes
• YARD docs are added or updated for the changes
• bundle exec rake passes locally (runs both the RSpec and Minitest suites)

[Copilot]

Pull request overview

This PR expands Rubyzen’s AST-wrapping API to reduce (or eliminate) raw RuboCop AST usage in lint rules by introducing first-class “value expression” and “assignment” primitives, plus new call-site convenience APIs. It also updates the sample project with new lint rules demonstrating the new APIs and bumps the gem version to 0.3.0.

Changes:

• Add ExpressionDeclaration (+ ExpressionsCollection) to model receivers/arguments/return values with kind predicates (constant/constructor/local var/hash literal/etc.).
• Add AssignmentDeclaration (+ AssignmentsProvider/AssignmentsCollection) and ReturnExpressionsProvider with collection bridges on methods/blocks.
• Extend CallSiteDeclaration with #arguments, #receiver_expression, and #enclosing_blocks, and add sample lint rules exercising these APIs.

Reviewed changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
spec/declarations/expression_declaration_spec.rb	Adds specs for expression predicates and call-site receiver/argument expression modeling.
spec/declarations/call_site_declaration_spec.rb	Adds specs for #receiver_expression, #arguments, and #enclosing_blocks.
spec/declarations/assignment_declaration_spec.rb	Adds specs for assignment name/value expression behavior (including masgn targets).
spec/collections/expressions_collection_spec.rb	Adds specs for expression collection filters and type-preserving filters.
spec/collections/assignments_collection_spec.rb	Adds specs for assignments collection name filtering and type preservation.
sample_project/src/tests/stubbing_test.rb	Adds sample “violation” source for stubbing Repos constants.
sample_project/src/tests/admin_flow_test.rb	Adds sample “violation” source for admin calls without context wrapper.
sample_project/src/serializers/user_serializer.rb	Adds sample class for “hash literal return” lint rule.
sample_project/src/questions/profile_status.rb	Adds sample class for “no side effects in questions” lint rule.
sample_project/spec/tests/no_stubbing_repos_lint_spec.rb	Adds lint rule using CallSiteDeclaration#arguments + ExpressionDeclaration#constant_name.
sample_project/spec/tests/admin_calls_use_with_admin_context_lint_spec.rb	Adds lint rule using CallSiteDeclaration#enclosing_blocks.
sample_project/spec/spec_helper.rb	Adds questions collection helper for question lint rules.
sample_project/spec/questions/no_side_effects_in_questions_lint_spec.rb	Adds lint rule using #receiver_expression + method #assignments to detect repo writes.
sample_project/spec/core/data_methods_return_data_objects_lint_spec.rb	Adds lint rule using #return_expressions.hash_literals.
lib/rubyzen/version.rb	Bumps gem version to 0.3.0.
lib/rubyzen/providers/return_expressions_provider.rb	Introduces provider for method/block return expressions.
lib/rubyzen/providers/enclosing_blocks_provider.rb	Introduces provider for retrieving enclosing blocks for a declaration.
lib/rubyzen/providers/assignments_provider.rb	Introduces provider for collecting local variable assignments.
lib/rubyzen/providers/arguments_provider.rb	Introduces provider for modeling call-site arguments as expressions.
lib/rubyzen/declarations/method_declaration.rb	Mixes in ReturnExpressionsProvider and AssignmentsProvider.
lib/rubyzen/declarations/expression_declaration.rb	Adds the new expression wrapper declaration and predicates/accessors.
lib/rubyzen/declarations/call_site_declaration.rb	Adds new call-site APIs and includes new providers.
lib/rubyzen/declarations/block_declaration.rb	Mixes in ReturnExpressionsProvider and AssignmentsProvider.
lib/rubyzen/declarations/assignment_declaration.rb	Adds the new assignment wrapper declaration.
lib/rubyzen/collections/methods_collection.rb	Adds collection bridges for return_expressions and assignments.
lib/rubyzen/collections/expressions_collection.rb	Adds expression collection filters (hash_literals, constants).
lib/rubyzen/collections/blocks_collection.rb	Adds collection bridges for return_expressions and assignments.
lib/rubyzen/collections/assignments_collection.rb	Adds the assignments collection type.
CLAUDE.md	Updates architecture docs with new APIs and data-flow.
CHANGELOG.md	Documents the 0.3.0 additions.