Implement Iterator.range

Summary

Implement the Stage 2 TC39 proposal: https://github.com/tc39/proposal-iterator.range

Add lazy Number and BigInt ranges with current endpoints, step/options, inclusive/exclusive, direction, validation, and numeric edge semantics.

Why

This proposal fits GocciaScript's modern ECMAScript surface and the 0.13.0 proposal roadmap. It should extend the engine's existing architecture rather than arrive as a userland shim.

Current behavior

The Iterator constructor and lazy helpers exist, but no standard range iterator does.

Expected behavior

Add lazy Number and BigInt ranges with current endpoints, step/options, inclusive/exclusive, direction, validation, and numeric edge semantics.

Scope notes

Use a dedicated concrete iterator inheriting from %Iterator.prototype%; never materialize or precompute large/infinite ranges. Cover NaN, infinities, signed zero, mixed types, docs, and proposal tests. Additive API: no flag.

Related bytecode roadmap: #871 and #875. Update the relevant language/built-in documentation and Goccia proposal inventory. Use the proposal repository and its current specification at implementation time; add focused project tests and matching pinned Test262/proposal coverage without regressions.

Acceptance criteria

• Parser/API surface, descriptors, evaluation order, errors, and observable protocol behavior match the current proposal.
• Implementation uses the identified shared engine seam without a duplicate compatibility shim.
• Focused positive, negative, abrupt-completion, and edge-case tests cover the proposal.
• Relevant project suites, pinned Test262 cases, formatting, and documentation checks pass.

Start with the existing Iterator constructor and lazy helpers, then compare their engine seam and observable behavior with the current TC39 proposal. Define the Number and BigInt range requirements from the proposal before adding focused project tests and pinned Test262 or proposal coverage. Done means proposal behavior, edge cases, documentation, inventory updates, and relevant checks pass without regressions.