docs(code-runtime): drop the remaining shipped claims for the private experimental backend

The review's final wording items: the portable-identifier note's Scope said the
backend 'has since shipped' without noting it is experimental/private; the
RESERVED_WORDS JSDoc said backends 'ship for both languages'. Both now name the
TypeScript backend as released and the CPython backend as experimental and
private. The package README also records that the truncation-marker text and
tempdir prefix keep the pre-rename short names (byte-anchored by tests,
independent of the npm name).

packages/experimental/code-runtime-python/README.zh.md

@@ -121,6 +121,7 @@ kind: "package-reference"
 - **1 秒双限 `ulimit -t 1` CPU 超限被报告为 `worker-exit` 而非 timeout**——当宿主在一个与软限相等的硬 CPU 限下启动且该限为 1 时，`_clamped` 无法下调软限，内核在同一 tick SIGKILL 忙循环，SIGXCPU 永远不会送达；隔离成立，只有分类降级。
 - **中间 binding 值没有字节上限**——实现仍受无损 JSON 序列化成本与进程内存约束，提供方或执行器可能应用自己的获取上限。
 - **真实 Loader 装配态快照推迟到 issue #1182 layer 5**——本包通过 `ctx.plugin(...)` 与真实子进程测试得到验证；完整的 dsh 应用组合（codeRuntime 经真实 Loader 注册）由该层一个受跟踪的装配测试覆盖，不由本包的测试套件承担。
+- **截断标记文本与临时目录前缀保留改名前的短名**——标记 `[dsh-code-runtime-python] log capture truncated at <N> bytes` 与 `dsh-code-runtime-python-` 临时目录前缀被测试逐字节锚定，且独立于 npm 包名；promotion（去掉 `experimental-` 前缀）不会重命名它们。
 
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 ### 开发备注