feat(dsl): Add shared_examples for reusable test patterns

[juvistr]

Summary

Add RSpec-style shared examples for reusable test patterns across types.

Motivation

• DRY: Eliminate duplicate tests for similar behaviors
• Consistency: Same tests applied to multiple implementations
• RSpec parity: Well-known pattern

Acceptance Criteria

• `shared_examples("name", (param) => { ... })` defines reusable block
• `include_examples("name", arg)` includes in context
• Parameters passed to shared block
• Works with nested describes
• Tests added
• Documentation updated

Example Usage

shared_examples("CRUD operations", (createFn) => {
    it("creates", () => {
        var item = createFn();
        expect(item).toNotBeNull();
        expect(item.Id).toBeGreaterThan(0);
    });
    
    it("reads", () => {
        var item = createFn();
        var loaded = service.Get(item.Id);
        expect(loaded).toBeEquivalentTo(item);
    });
});

describe("UserService", () => {
    include_examples("CRUD operations", () => service.Create(new User("Alice")));
});

describe("TodoService", () => {
    include_examples("CRUD operations", () => service.Create(new Todo("Task")));
});

Implementation Notes

• Store shared examples in registry by name
• Clone context when including
• Handle parameter binding

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity.
It will be closed in 14 days if no further activity occurs.
Thank you for your contributions!