feat(orchestration/audit): 子代理上下文可审计查询（全量/尾部/关键词定位）+ 主代理代审授权（审计日志+小字）

internal/runtime/orchestration/audit/audit.go

@@ -0,0 +1,24 @@
+// Package audit provides the subagent-auditing primitives specified by the
+// Cyrene orchestration design (DevDocs/design/05-子代理.md §3 and §6) and the
+// security/audit requirements in DevDocs/design/11-安全与权限.md §4 and §8.
+//
+// It has two halves:
+//
+//   - ContextAuditor gives a main agent read-only, traceable access to a
+//     subagent's context (a []model.Message) so it can audit and pinpoint what
+//     the subagent did: the full context, a tail window, or a keyword hit with
+//     its surrounding lines. It is a pure value type over the message list the
+//     orchestral layer hands it; it holds no storage and no policy.
+//
+//   - Approver records a main-agent review-and-approve (代审授权) of a
+//     subagent's sensitive action. It writes a structured audit log (who / what
+//     / when / result) and produces the short frontend notice "「xxx 想要干什么，
+//     我审查后批准了」". Whether an action is actually sensitive and whether it is
+//     allowed is decided by the upper policy layer; this package only records,
+//     narrates, and returns the result model — it never judges permission.
+//
+// The package is a leaf: it depends only on the standard library,
+// internal/runtime/model and internal/logger, and never imports the agent loop
+// or other runtime packages, so it can sit inside runtime/orchestration without
+// an import cycle.
+package audit