feat(butler): upgrade ButlerRouter to semantic skill routing

Replace keyword-only ButlerRouter with SemanticSkillRouter (TF-IDF).
75 skills now participate in intent classification instead of 4 hardcoded domains.

- Expose ButlerRouterBackend trait + RoutingHint as pub
- Add with_router() constructor for injecting custom backends
- Add SemanticRouterAdapter in kernel layer (bridges skills ↔ runtime)
- Enhance context injection with skill-level match info

crates/zclaw-runtime/src/middleware/butler_router.rs

@@ -24,16 +24,20 @@ pub struct ButlerRouterMiddleware {
 }
 
 /// Backend trait for routing implementations.
+///
+/// Implementations can be keyword-based (default), semantic (TF-IDF/embedding),
+/// or any custom strategy. The kernel layer provides a `SemanticSkillRouter`
+/// adapter that bridges `zclaw_skills::SemanticSkillRouter` to this trait.
 #[async_trait]
-trait ButlerRouterBackend: Send + Sync {
+pub trait ButlerRouterBackend: Send + Sync {
     async fn classify(&self, query: &str) -> Option<RoutingHint>;
 }
 
 /// A routing hint to inject into the system prompt.
-struct RoutingHint {
-    category: String,
-    confidence: f32,
-    skill_id: Option<String>,
+pub struct RoutingHint {
+    pub category: String,
+    pub confidence: f32,
+    pub skill_id: Option<String>,
 }
 
 // ---------------------------------------------------------------------------
@@ -126,6 +130,14 @@ impl ButlerRouterMiddleware {
         Self { _router: None }
     }
 
+    /// Create a butler router with a custom semantic routing backend.
+    ///
+    /// The kernel layer uses this to inject `SemanticSkillRouter` from `zclaw-skills`,
+    /// enabling TF-IDF + embedding-based intent classification across all 75 skills.
+    pub fn with_router(router: Box<dyn ButlerRouterBackend>) -> Self {
+        Self { _router: Some(router) }
+    }
+
     /// Domain context to inject into system prompt based on routing hint.
     fn build_context_injection(hint: &RoutingHint) -> String {
         let domain_context = match hint.category.as_str() {
@@ -133,13 +145,29 @@ impl ButlerRouterMiddleware {
             "data_report" => "用户可能在请求数据统计或报表相关的工作。请优先提供结构化的数据和建议。",
             "policy_compliance" => "用户可能在咨询政策法规或合规要求。请引用具体政策文件并给出明确的合规建议。",
             "meeting_coordination" => "用户可能在处理会议协调或行政事务。请提供简洁的待办清单或行动方案。",
+            "semantic_skill" => {
+                // Semantic routing matched a specific skill
+                if let Some(ref skill_id) = hint.skill_id {
+                    return format!(
+                        "\n\n[语义路由] 匹配技能: {} (置信度: {:.0}%)\n系统检测到用户的意图与已注册技能高度相关，请在回答中充分利用该技能的能力。",
+                        skill_id,
+                        hint.confidence * 100.0
+                    );
+                }
+                return String::new();
+            }
             _ => return String::new(),
         };
 
+        let skill_info = hint.skill_id.as_ref().map_or(String::new(), |id| {
+            format!("\n关联技能: {}", id)
+        });
+
         format!(
-            "\n\n[路由上下文] (置信度: {:.0}%)\n{}",
+            "\n\n[路由上下文] (置信度: {:.0}%)\n{}{}",
             hint.confidence * 100.0,
-            domain_context
+            domain_context,
+            skill_info
         )
     }
 }