refactor(code-runtime-python): move the package into packages/experimental

The CPython code runtime's complete public contract is experimental, so it
moves to packages/experimental per the experimental-packages rules: npm name
@deepseek-ai/dsh-experimental-code-runtime-python, private: true, no
publishConfig. All references updated (code-runtime READMEs, config-catalog
and module-graph regenerated with zh alignment, tsconfig paths, doc-standard
and workspace-constraints scripts, the fd-3 and settlement Agent Notes, and
the package README links); md-links and translation pairing pass, and the
suite still runs green.

packages/experimental/code-runtime-python/src/invariant.ts

@@ -0,0 +1,33 @@
+/**
+ * Package-owned invariant companion for `@deepseek-ai/dsh-code-runtime-python`.
+ * @module @deepseek-ai/dsh-code-runtime-python/invariant
+ */
+
+/* jscpd:ignore-start */
+import type { Context } from '@deepseek-ai/cordis'
+import type { InvariantInstaller } from '@deepseek-ai/dsh-invariants'
+
+const PACKAGE_NAME = '@deepseek-ai/dsh-code-runtime-python'
+
+/** Cordis companion plugin name. */
+export const name = 'code-runtime-python-invariant'
+/** Service required before the companion can reserve package ownership. */
+export const inject = ['invariants']
+
+/**
+ * No runtime invariant: every relation this backend maintains — frame ordering, budget accounting,
+ * and process teardown — lives in the CPython subprocess or on the fd-3 wire, so no same-process
+ * event sequence or mutable data relation is observable from a Cordis listener. `protocol.spec.ts`,
+ * `protocol-mirror.e2e.ts`, and the real-subprocess `runtime.spec.ts` cover that behavior, matching
+ * the sibling process-boundary backend `@deepseek-ai/dsh-code-runtime-worker-thread`.
+ */
+const install: InvariantInstaller = () => {}
+
+/**
+ * Register this package's invariant companion.
+ * @param ctx - Cordis context carrying the invariant service.
+ * @returns the installed registration's disposer after setup succeeds.
+ */
+export const apply = (ctx: Context): Promise<() => void> =>
+  Promise.resolve(ctx.invariants.register(PACKAGE_NAME, install))
+/* jscpd:ignore-end */