docs: give subsystems/ its own README index; retire the data-structures-catalog framing

core.md doubled as the folder index: its intro claimed "this folder catalogs the data structures" and carried the 38-row page table, wording that predates the one-page-per-subsystem shape where every page also carries its generated Cordis surface. The folder index now lives in docs/subsystems/README.md (page table plus the type-equiv note), and core.md is one subsystem page among siblings: the spine vocabulary. Structural referents move with it: the docs/AGENTS.md tier table and update rule, development.md's type-equiv pointer, the dsh-code-review skill, the two owning catalog Agent Notes, and website/docs.ts (README projects as reference/subsystems/index.md and takes the docs/subsystems folder alias; sidebar orders shift by one). Remaining "data-structure catalog" / "sub-page" phrasing in active notes and READMEs is reworded to subsystem-page terms in both languages; touched pairs re-recorded; translation-prompt snapshot re-recorded (its example embeds development.md).

packages/subprocess/subprocess/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/subprocess/subprocess/README.md
-README.md: 6e4b9a9c50bc54a4752930ec14269d2c15233a76
-README.zh.md: d756cd9b7117d7ce9a2e79c6469d9fc188c9600b
+README.md: c28361f5e767f81fe8d1ca4757aece83dccfea5c
+README.zh.md: 3ad73bdea3b137f1c9139fdb1b52c49eb10b5500

packages/subprocess/subprocess/README.md

@@ -15,7 +15,7 @@ The subprocess seam (`ctx.subprocess`) is the process half of one execution worl
 - `scrubbedParentEnv()` / `SENSITIVE_ENV_PATTERN` are the one shared scrub definition: ambient credential-shaped and `DSH_*` names are dropped, and explicit `env` merges after the scrub. The local ordinary and terminal spawns both apply it; SDK-managed transports that own their spawn may import it directly.
 - Disposal of the service terminates all still-running managed processes and awaits their exit.
 
-See the [subprocess data-structure catalog](../../../docs/subsystems/subprocess.md) and the [seam Agent Note](../../../.agents/notes/implemented/architecture/2026-07-26-subprocess-seam.md).
+See the [subprocess subsystem page](../../../docs/subsystems/subprocess.md) and the [seam Agent Note](../../../.agents/notes/implemented/architecture/2026-07-26-subprocess-seam.md).
 
 ## Model Experience
 

packages/subprocess/subprocess/README.zh.md

@@ -15,7 +15,7 @@
 - `scrubbedParentEnv()` / `SENSITIVE_ENV_PATTERN` 是唯一一份共享的环境清理定义：环境中形似凭据的名称与 `DSH_*` 名称都会被丢弃，显式 `env` 在清除之后合并。本地的普通 spawn 与终端 spawn 都应用该定义；拥有自身 spawn 的 SDK 管理传输可直接导入它。
 - 服务自身的 dispose（资源释放）会终止所有仍在运行的受管进程并等待其退出。
 
-参见[子进程数据结构目录](../../../docs/subsystems/subprocess.md)与[seam Agent Note（agent 决策记录）](../../../.agents/notes/implemented/architecture/2026-07-26-subprocess-seam.md)。
+参见[子进程子系统页面](../../../docs/subsystems/subprocess.md)与[seam Agent Note（agent 决策记录）](../../../.agents/notes/implemented/architecture/2026-07-26-subprocess-seam.md)。
 
 ## 模型体验