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/compact/compact/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/compact/compact/README.md
-README.md: 5703540435b976cfc03987edca28e2b5cd24ae0d
-README.zh.md: 434b9bfa3d0d7f21fc262929ac72ff5ab15d5057
+README.md: 2bf39cac91798b1e0fdb679d2a9b674caceffe22
+README.zh.md: 330b5b0cb9d5c2bf3953354112f3488447e71f87

packages/compact/compact/README.md

@@ -24,7 +24,7 @@ All three operations are **abstract** — the backend owns trigger policy, reten
 | `compactNow(agent, signal)` | Explicitly compact one useful balanced older span even below automatic pressure. It synchronously reserves idle turn admission before yielding, writes nothing when no useful span exists, records a standalone `compact/* { turn: null }` attempt before summarization, and awaits its durability checkpoint before release. Expected operational failures use `ManualCompactionError`; cancellation rethrows the exact abort reason. |
 | `compactRegion(start, end, agent, signal?)` | Forcibly summarize surface nodes `[start, end]` (inclusive seqs) from `agent.session` into a single replacement node whose source is `COMPACT_CHECKPOINT_SOURCE`. **Throws** if a compaction is already in progress, if `start`/`end` aren't surface nodes, or if `start` is positioned after `end` on the surface. The range is a SURFACE-POSITION span, not a numeric seq interval — after a prior replace lands a fresh high-seq summary node at the shadowed range's position, surface order no longer tracks seq order. |
 
-`CompactionResult` keeps the raw summary and bookkeeping-event seqs available to callers alongside the shadowed range and token accounting; its drift-checked shape lives in the [compaction data-structure reference](../../../docs/core-data-structures/compaction.md#compactionresult).
+`CompactionResult` keeps the raw summary and bookkeeping-event seqs available to callers alongside the shadowed range and token accounting; its drift-checked shape lives in the [compaction data-structure reference](../../../docs/subsystems/compaction.md#compactionresult).
 
 `compactIfNeeded` and `compactNow` take a required `signal`; `compactRegion`'s is optional. A backend that summarizes via `ctx.llm.stream()` **must** forward it into the call's `GenerateOptions.signal`, so an abort or fiber dispose tears down the in-flight summarization. Automatic and explicit-region brackets recover their numeric owner from the currently open turn. Manual brackets require no open turn and stamp `turn: null`.
 

packages/compact/compact/README.zh.md

@@ -24,7 +24,7 @@
 | `compactNow(agent, signal)` | 即使未达到自动压力，也显式压缩一段有效、平衡的较早范围。该操作会在让出控制权前同步预留空闲轮次接纳；没有有效范围时不写入任何内容；在摘要前记录独立的 `compact/* { turn: null }` 尝试；释放预留前等待其持久性检查点。预期操作失败使用 `ManualCompactionError`；取消会原样重新抛出 abort 原因。 |
 | `compactRegion(start, end, agent, signal?)` | 强制将表层节点 `[start, end]`（包含两端 seq）从 `agent.session` 摘要为单个替换节点，其源为 `COMPACT_CHECKPOINT_SOURCE`。如果压缩已在进行、`start`／`end` 不是表层节点，或 `start` 在表层上位于 `end` 之后，则**抛出异常**。该范围是表层位置范围，不是数值 seq 区间：在之前的 replace 将新生成的高 seq 摘要节点放到已遮蔽范围的位置之后，表层顺序不再跟随 seq 顺序。 |
 
-`CompactionResult` 向调用方保留原始摘要与记录操作过程的事件 seq，同时保留已遮蔽范围与 token 计量；其结构由漂移检查保障，定义见 [压缩数据结构参考](../../../docs/core-data-structures/compaction.md#compactionresult)。
+`CompactionResult` 向调用方保留原始摘要与记录操作过程的事件 seq，同时保留已遮蔽范围与 token 计量；其结构由漂移检查保障，定义见 [压缩数据结构参考](../../../docs/subsystems/compaction.md#compactionresult)。
 
 `compactIfNeeded` 和 `compactNow` 必须传入 `signal`；`compactRegion` 的该参数可选。通过 `ctx.llm.stream()` 摘要的后端**必须** 将它转发到调用的 `GenerateOptions.signal`，因此 abort 或 fiber dispose（资源释放）会停止进行中的摘要。自动和显式范围标记对会从当前打开的轮次恢复其数字形式归属。手动标记对不要求存在打开的轮次，并标记 `turn: null`。