feat: implement /v1/models endpoint

Added OpenAI-compatible model listing endpoint using the registry data.

internal/server/server.go

@@ -89,6 +89,7 @@ func (s *Server) setupRoutes() {
 	v1 := s.router.Group("/v1")
 	{
 		v1.POST("/chat/completions", s.handleChatCompletions)
+		v1.GET("/models", s.handleListModels)
 	}
 
 	// Dashboard API Group
@@ -140,6 +141,34 @@ func (s *Server) setupRoutes() {
 	})
 }
 
+func (s *Server) handleListModels(c *gin.Context) {
+	type OpenAIModel struct {
+		ID      string `json:"id"`
+		Object  string `json:"object"`
+		Created int64  `json:"created"`
+		OwnedBy string `json:"owned_by"`
+	}
+
+	var data []OpenAIModel
+	if s.registry != nil {
+		for pID, pInfo := range s.registry.Providers {
+			for mID := range pInfo.Models {
+				data = append(data, OpenAIModel{
+					ID:      mID,
+					Object:  "model",
+					Created: 1700000000, // Static placeholder
+					OwnedBy: pID,
+				})
+			}
+		}
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"object": "list",
+		"data":   data,
+	})
+}
+
 func (s *Server) handleChatCompletions(c *gin.Context) {
 	startTime := time.Now()
 	var req models.ChatCompletionRequest