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.

docs/subsystems/token-meter.zh.md

@@ -0,0 +1,43 @@
+# Token 计量
+
+[English](token-meter.md) | 中文
+
+`@deepseek-ai/dsh-token-meter` 公开一个独立的回放快照，用于表示请求压力与按位置计算的表层定价。`logRevision` 表示生成该计量中每个字段时所消费的持久事件数量。
+
+来源：[`packages/llm/token-meter/src/types.ts`](../../packages/llm/token-meter/src/types.ts)
+
+## `TokenMeasurement`
+
+```ts type-equiv
+/** Detached immutable request-pressure and surface snapshot at one consumed log revision. */
+interface TokenMeasurement {
+  /** Number of durable events consumed; equal to the next unread event seq. */
+  readonly logRevision: number
+  /** Provider or heuristic anchor used for this measurement. */
+  readonly baseline: TokenMeasurementBaseline
+  /** Signed repricing of current surface content relative to the baseline anchor. */
+  readonly surfaceDeltaTokens: number
+  /** Non-negative current request-and-response pressure. */
+  readonly totalTokens: number
+  /** Total heuristic tokens across the current surface. */
+  readonly surfaceTokens: number
+  /** Current surface nodes in positional head-to-tail order. */
+  readonly nodes: readonly TokenSurfaceNode[]
+}
+```
+
+`baseline.kind === 'usage'` 表示最近一次成功的提供方调用具有相同的规范请求信封，且该调用的总量不低于其完整启发式锚点。`estimated` 表示不存在可复用的保守 usage 锚点，因此服务使用固定启发式规则对完整信封和表层定价。后续成功请求会替换早先的锚点；有符号的 `surfaceDeltaTokens` 会保留相对于匹配锚点的增长与缩减。`totalTokens` 仍表示请求与响应压力，`surfaceTokens` 则是仅针对表层的启发式总量，等于所有节点价格之和。
+
+## `TokenSurfaceNode`
+
+```ts type-equiv
+/** One token-priced node in the current ordered session surface. */
+interface TokenSurfaceNode {
+  /** Durable sequence number of the surface event. */
+  readonly seq: number
+  /** Heuristic tokens for the exact message projected by this node. */
+  readonly tokens: number
+}
+```
+
+表层顺序具有权威性；替换节点的持久 seq 可能高于位置排在其后的节点。该快照不可变，不会随底层回放折叠推进而增长。