docs: drop the as-of date stamps from prose

A reader dates a book by the book. An inline 截至 <date> or （核验日期：<date>）
tells them nothing they cannot infer, and it decays: this cluster's clearest
case is the eight files that carried 截至 2026-05-18 while git showed they were
written 33 days earlier, one commit having later nudged the date a day for
visual consistency.

Two kinds of date deliberately survive, because they are not as-of stamps:

- Forward-looking deadlines. "Sonnet 5 的 $2/$10 是截至 2026-08-31 的介绍价"
  states when a price expires; deleting that date would lose a fact.
- Ledger metadata. verified_at / expires_at / ttl_days in the volatile-facts
  appendices are inputs to check_volatile_facts(), which fails the build when
  they lapse. That is the right home for a verification date — machine-checked
  and self-expiring, rather than prose nothing re-earns.

Event dates are untouched throughout (2026-06-09 GA, 2026-06-12 暂停). Where a
sentence needed the sequence, "截至 2026-07-09 官方模型页已恢复" became
"官方模型页此后已恢复", which keeps the ordering without the observation date.

17_ecosystem/README.md

@@ -1,6 +1,6 @@
 # 第十七章 容器其它生态
 
-> **版本说明（核验日期：2026-05-16）**：本章介绍的工具和运行时（Podman、Buildah、Skopeo、containerd、Kata Containers、gVisor、WasmEdge 等）都保持活跃的开发。建议：
+> **版本说明**：本章介绍的工具和运行时（Podman、Buildah、Skopeo、containerd、Kata Containers、gVisor、WasmEdge 等）都保持活跃的开发。建议：
 > - 查阅各项目官方文档获取最新版本
 > - 在生产环境使用前验证版本兼容性
 > - 关注官方发布说明了解重大变更