docs(code-runtime): stop calling the private experimental Python backend published

The review's carry-over: 'each has a published backend' in the CodeRuntime
JSDoc and its projections (tool-cordis api-catalog, subsystems page) plus
'both shipped'/'backends ship' in the code-runtime README all claimed the
Python backend is released; it is private and experimental, excluded from the
release family. The wording now states the TypeScript backend is released and
the Python backend is experimental and private (not published), in the JSDoc
(api-catalog regenerated to match), the READMEs (paired), and the subsystems
page (paired).

packages/code-runtime/code-runtime/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/code-runtime/code-runtime/README.md
-README.md: b33fec41abe516a047ea52112888bc165a63dffa
-README.zh.md: ac548f8318fb82c5e68558d1e638193738125d46
+README.md: 507b9f13539abbf31250385657f54d9f1d18e777
+README.zh.md: 2fd76fce6bb426e377d42572fa3754a1cab7cd33

packages/code-runtime/code-runtime/README.md

@@ -94,7 +94,7 @@ Binding-global and error-class names are language-portable: they must match the
 <a id="further-exploration"></a>
 ## Further Exploration
 
-Read these when the package-level contract is not enough. They move from the PTC mode consumer to the shipped backends and the capability-seam model.
+Read these when the package-level contract is not enough. They move from the PTC mode consumer to the backends and the capability-seam model.
 
 - [PTC mode Agent Note](../../../.agents/notes/implemented/feature/2026-06-15-ptc.md) — how the tool registry consumes `ctx.codeRuntime` and presents `run_code` to the model.
 - [Worker-thread backend](../code-runtime-worker-thread/README.md) — the shipped TypeScript execution backend.

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

@@ -94,7 +94,7 @@ binding-global 与 error-class 名称是语言可移植的：必须匹配标识
 <a id="further-exploration"></a>
 ## 进一步探索
 
-当包级约定不够用时阅读以下内容。它们从 PTC mode 消费方进入已发布的后端与能力 seam 模型。
+当包级约定不够用时阅读以下内容。它们从 PTC mode 消费方进入后端与能力 seam 模型。
 
 - [PTC mode Agent Note](../../../.agents/notes/implemented/feature/2026-06-15-ptc.zh.md)——工具注册表如何消费 `ctx.codeRuntime` 并把 `run_code` 呈现给模型。
 - [Worker 线程后端](../code-runtime-worker-thread/README.zh.md)——已发布的 TypeScript 执行后端。

packages/code-runtime/code-runtime/src/index.ts

@@ -106,7 +106,8 @@ export abstract class CodeRuntime extends Service {
    * generates language-specific presentation (typed SDK stubs, usage
    * instructions) switches on it and fails loud on a language it cannot
    * present. Well-known values: `'typescript'` and `'python'`, those
-   * `dsh-tools` presents; each has a published backend.
+   * `dsh-tools` presents; the TypeScript backend is released, the Python
+   * backend is experimental and private (not published).
    */
   abstract readonly language: string