docs: polish v0.1.2 public collection guidance

[LightDevCoder]

Summary

• make the homepage limitation language user-friendly while retaining the detailed BLOCKED independent-evaluator evidence in release documentation
• document external workflow capabilities and preserve the first-party ownership boundary
• align grill-me as the user-facing entry with grilling as the underlying capability
• improve Chinese documentation independence and Chinese-first navigation, including the Quick Start guide

Validation

• Quick Start smoke: 8 assertions, PASS
• Collection discovery: 689 assertions, PASS
• Chinese relative-link check: PASS
• staged diff whitespace check: PASS

The independent evaluator evidence limitation remains explicitly BLOCKED and is not changed by this documentation polish.