Publish a horizon for Samples keyword aliases

## What to build

Give the deprecated Samples camelCase keyword aliases one published removal horizon through the package's shared deprecation mechanism. The aliases were introduced on 2026-08-07; use 2027-08-07, matching the repository's one-year horizon convention.

Both Samples getters must read that date from the central removal table and continue accepting and translating every legacy keyword exactly as they do now. This ticket schedules the aliases; it does not remove them or change their wire spellings.

## Acceptance criteria

- [ ] The central removal table contains one Samples-scoped horizon of 2027-08-07.
- [ ] Both Samples legacy-keyword shims emit advisories that name the usable replacement and print that horizon.
- [ ] No Samples deprecation still says only "in a future release."
- [ ] Tests obtain the expected horizon from the central table rather than duplicating the date literal.
- [ ] Every camelCase alias remains accepted and produces the same request as its snake_case replacement.
- [ ] Public signatures, parameter mappings, and Samples wire names are unchanged.
- [ ] The full offline suite and coverage gate pass.

## Blocked by

None — can start immediately.

首先定位共享的中央移除表和 Samples 的两个 legacy-keyword getter，然后检查它们现有的 deprecation 测试以及 request-mapping 行为。添加唯一的 2027-08-07 时间节点，并验证 advisories、未更改的 alias 翻译、完整的 offline suite 和 coverage gate。

由索引模型根据 Issue 内容生成。