docs(spec): 给 rls.zod.ts using 上方那段过时语法规范打 STALE 标记,指向 #6919

PR #6918 修好了 `using` 的 `.describe()`,但同属性上方 45 行处的 TSDoc 块
(`:313`「Exactly four forms compile」)仍是旧说法。改之前两处一致地错,改
之后两处互相矛盾 —— 而读源码的人(常常是 AI,ADR-0033)先撞上的是那段更长、
更像权威的语法规范,没有任何信号提示下方那一行 `.describe()` 才是当前事实。

这里只加标记,不重写:重写那 60 行语法规范散文(连同 5 条 SQL 方言的
`@example`)是 #6919 自己的卡,塞进这张两条目 sweep 卡会破坏其 per-item
复核模型。标记把「两条互相矛盾的断言」降级为「一条断言 + 一句诚实警告」,
直到真正的修复落地。

该块不进生成器(gen:docs 只渲染 `.describe()` 与模块级 docblock),已实测
确认:加这段标记后 content/docs/references/** 零 diff。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018ffcE95NaMJcL9XJ9VDYgk

Author: claude

packages/spec/src/security/rls.zod.ts

@@ -309,6 +309,12 @@ export const RowLevelSecurityPolicySchema = lazySchema(() => strictObject(
    *
    * **Supported expression grammar (reference compiler)**
    *
+   * ⚠️ **STALE — the enumeration below UNDER-states what compiles (#6919).**
+   * The `.describe()` on this property carries the current truth: `!=`, the
+   * ordering comparisons, `in` over an inline literal list, `&&`, `||` and a
+   * bare `true` all lower today. Rewriting this block is tracked in #6919; do
+   * not read the four-item list as the accepted set.
+   *
    * The reference RLS compiler implements a deliberately **small, fixed
    * grammar** rather than a general SQL parser. Exactly four forms compile;
    * anything else fails closed (the policy matches zero rows). Keep `using`