[argszero]

Summary

Finalizes the points model (纯分享经济) in docs/user-stories.md (v1.1 → v1.2), per host rant 2026-08-14T20:20:46 「点数机制定案 — 纯分享经济 + 新人赠送 10 点（有 1 周有效期），分享收益与充值点数永久有效」:

• Gift points: every new registered user receives 10 points (新人体验券), valid for 1 week from grant — unused gift points expire / 清零 automatically.
• Earned points (from sharing): permanent.
• Top-up points: permanent (top-up channel not yet supported, but the rule is fixed now).
• Deduction order: consumption deducts expiring (gift) points first, then permanent points.
• New stories US-22 (new user receives 10 gift points), US-23 (see point source & validity), US-24 (sharer earnings permanent), and edge case E-13 (gift-point expiry) added.
• Updated scene description: the public edition currently has no top-up channel — new users start with the 10-point gift, long-term points come from sharing.

This is PR 1 of 2 for the rant (docs first, per the rant's 处理方式). PR 2 (UI prototype on feat/points-model-ui) follows.

Related Issue

No issue — host rant 2026-08-14T20:20:46.981288 (project argszero/aitokenpool).

Changes

• 功能/修复说明: points model v1.2 documented (gift/earned/top-up validity + deduction order)
• 涉及配置/数据结构的改动已同步示例文件: n/a (docs only)

Tests

• cargo test 全部通过 (1 passed)
• cargo fmt --check 通过
• 新增/更新了单元测试（如适用）: n/a (docs only)

Checklist

• 分支命名符合约定: docs/points-model
• Commit message 使用 Conventional Commits 格式: docs: finalize points model …
• 单一职责，改动最小化 (docs/user-stories.md only)