docs: rename core-data-structures/ to subsystems/

The folder is becoming the home of one-doc-per-subsystem pages (intro +
data structures + cordis services/events), so the name must describe the
whole contract, not just the type-vocabulary third of it. Mechanical
rename rebuilt on current master: every inbound Markdown link, generator
constant, website route, type-equiv manifest path, and spec expectation
moves together; the zh sides of the notes whose prose names the folder
are aligned (子系统) in the same change; touched bilingual pairs
re-recorded; translation-prompt snapshot re-recorded (its example embeds
development.md). Historical Agent Note slugs keep their dated
filenames.

packages/core/tools/src/index.ts

@@ -39,7 +39,7 @@ import { renderToolsSdkPy } from './py-types.ts'
  * the flavor table is checked against too, so any of the three left out is a
  * typecheck failure. What no check reaches is the prose that names the values
  * instead of deriving them: the seam's `dsh-code-runtime` README pair, its
- * `CodeRuntime.language` JSDoc, and `docs/core-data-structures/code-runtime.md`
+ * `CodeRuntime.language` JSDoc, and `docs/subsystems/code-runtime.md`
  * with its zh pair, plus this package's own README pair and the
  * {@link Config.mode} JSDoc.
  */