fix: health endpoint + graph/edge API + normalizeEntity Chinese + nl_query comparison

1. Add /api/v1/health endpoint (maps to HandleHealth)
2. Add POST /api/v1/graph/edge for adding relation edges
3. Fix normalizeEntity to preserve Chinese characters (0x4e00-0x9fa5)
4. Fix nl_query direct_path comparison to use normalizeEntity on both sides

go/internal/api/server.go

@@ -31,9 +31,10 @@ func normalizeEntity(entity string) string {
 	if strings.HasPrefix(entity, "n_") {
 		entity = entity[2:]
 	}
-	// 过滤特殊字符
+	// 保留中文、字母、数字、下划线、连字符，过滤其他特殊字符
 	clean := strings.Map(func(r rune) rune {
-		if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || r == '_' || r == '-' {
+		if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || r == '_' || r == '-' ||
+			(r >= 0x4e00 && r <= 0x9fa5) { // 中文 Unicode 范围
 			return r
 		}
 		return '_'
@@ -278,6 +279,7 @@ func NewServer() http.Handler {
 	// 后续在 catch-all 中处理（见文件末尾）
 
 	mux.HandleFunc("/health", routes.HandleHealth)
+	mux.HandleFunc("/api/v1/health", routes.HandleHealth)
 	// ─── Prometheus /metrics ─────────────────────
 	mux.Handle("/metrics", metrics.Handler())
 
@@ -333,6 +335,38 @@ func NewServer() http.Handler {
 	mux.HandleFunc("/api/v1/graph/stats", graphAPI.Stats)
 	mux.HandleFunc("/api/v1/graph/query", graphAPI.Query)
 	mux.HandleFunc("/api/v1/graph/navigate", graphAPI.Navigate)
+	// 新增：添加关系边（POST JSON body: {"from":"实体A","to":"实体B","relation":"关系类型","namespace":""}）
+	mux.HandleFunc("/api/v1/graph/edge", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			http.Error(w, "POST only", 405)
+			return
+		}
+		var req struct {
+			From      string `json:"from"`
+			To        string `json:"to"`
+			Relation  string `json:"relation"`
+			Namespace string `json:"namespace"`
+		}
+		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+			http.Error(w, err.Error(), 400)
+			return
+		}
+		if req.From == "" || req.To == "" || req.Relation == "" {
+			http.Error(w, "from, to, relation required", 400)
+			return
+		}
+		ns := req.Namespace
+		if ns == "" {
+			ns = "default"
+		}
+		edgeID := fmt.Sprintf("e_%s_%s_%d", req.From, req.Relation, time.Now().UnixNano())
+		err := graphStore.AddEdge(edgeID, req.From, req.To, req.Relation, ns, 1.0)
+		if err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+		json.NewEncoder(w).Encode(map[string]interface{}{"status": "ok", "edge_id": edgeID})
+	})
 	// 新增：pagerank + evidence_count
 	mux.HandleFunc("/api/v1/graph/pagerank", func(w http.ResponseWriter, r *http.Request) {
 		rank := graphStore.PageRank(0.85, 20)
@@ -478,7 +512,9 @@ func NewServer() http.Handler {
 			// 找 A → B 的直接边
 			var directPath map[string]interface{}
 			for _, p := range paths {
-				if strings.TrimPrefix(p["to"].(string), "n_") == normalizeEntity(entityB) {
+				toNorm := normalizeEntity(p["to"].(string))
+				targetNorm := normalizeEntity(entityB)
+				if toNorm == targetNorm {
 					directPath = p
 					break
 				}