docs(comments): 注释中文化 · internal/runtime/model + internal/services/backthink（54 文件，纯替换）

- 只翻注释/文档字符串：`go/scanner` 剥注释后按 token 序列+literal 逐 token 比对，**54/54 文件 SAME**；
  改动文件总行数与 HEAD 漂移 = 0（严格 1:1，无合并/拆行）
- 裁决编号与 design 节号逐字保留（03.4.1/03.4.2/03.4.3/14.4.1/14.4.5/07.4.2-4、design/04 §3.1/§3.2 等）；
  `chat_template_kwargs` / `enable_thinking` / `reasoning_effort` / `thinking:{type}` 字段名与形状说明未动
- 存疑译法（已登记）：`persona` 在叙事语境用「角色」、标识符语境保留 `persona`（仓库既有模块本身混用）；
  `rung`→「级」；`provider` 存在「提供商/提供者」两种落笔（可按需一键统一）
- 复核：build/vet 绿 + 两包测试绿；gofmt 干净；残留英文注释 0 条
- 既有存量（未修，只报告）：`model/anthropic_test.go` 612 行 >500；`applyAnthropicEvent` 115 行 >80

internal/services/backthink/sinks.go

@@ -1,14 +1,14 @@
 package backthink
 
-// The production composition root builds the gateway hub and the channel bridge
-// *after* backthink.New (the hub needs the loop, the bridge needs the loop and
-// owner profile, both of which are assembled later), so the ActiveClient and
-// IMAdapter sinks are unavailable at construction time. These setters inject them
-// once the gateway / bridge exist and rebuild the pusher, keeping the resolved
-// rate gate so a later push routes correctly.
+// 生产组合根在 backthink.New *之后* 才构建 gateway hub 与 channel
+// bridge（hub 需要 loop，bridge 需要 loop 与主人档案，
+// 两者都在更晚时才组装），因此构造时拿不到 ActiveClient 与
+// IMAdapter 槽。这些设置器在 gateway / bridge 存在后注入它们，
+// 并重建推送器，同时保留已解出的
+// 频率门，使之后的推送路由正确。
 
-// SetActiveSink wires the production active web/native client sink (the gateway
-// hub) and rebuilds the pusher. Call it after the gateway exists, before Start.
+// SetActiveSink 接入生产用的活跃 Web/原生客户端槽（gateway
+// hub）并重建推送器。请在 gateway 存在之后、Start 之前调用。
 func (b *Backthink) SetActiveSink(active ActiveClient) {
 	b.mu.Lock()
 	defer b.mu.Unlock()
@@ -16,8 +16,8 @@ func (b *Backthink) SetActiveSink(active ActiveClient) {
 	b.rebuildPusherLocked()
 }
 
-// SetIMSink wires the production IM bridge sink (the channel bridge) and rebuilds
-// the pusher. Call it after the channel bridge exists, before Start.
+// SetIMSink 接入生产用的 IM 桥槽（channel bridge）并重建
+// 推送器。请在 channel bridge 存在之后、Start 之前调用。
 func (b *Backthink) SetIMSink(im IMAdapter) {
 	b.mu.Lock()
 	defer b.mu.Unlock()
@@ -25,14 +25,14 @@ func (b *Backthink) SetIMSink(im IMAdapter) {
 	b.rebuildPusherLocked()
 }
 
-// rebuildPusherLocked replaces the pusher from the current sinks, gate and push
-// outlet. The caller must hold b.mu.
+// rebuildPusherLocked 用当前槽位、频率门与推送出口替换
+// 推送器。调用方必须持有 b.mu。
 func (b *Backthink) rebuildPusherLocked() {
 	b.pusher = newPusher(b.deps.Active, b.deps.IM, b.gate, b.log).withExporter(b.deps.Exporter)
 }
 
-// currentPusher returns the active pusher under the lifecycle lock, so a sink
-// swap never races with a concurrent thinking pass that is about to push.
+// currentPusher 在生命周期锁下返回当前推送器，因此一次槽位
+// 换入绝不会与即将推送的并发思考轮发生竞态。
 func (b *Backthink) currentPusher() Pusher {
 	b.mu.Lock()
 	defer b.mu.Unlock()