fix(server): release MatchResult back to pool after use

Add matcher.ReleaseMatchResult(result) in the base handler to prevent
sync.Pool object leak. Every Match() call acquires from pool but the
caller never returned objects, causing unbounded pool growth.

internal/server/server.go

@@ -529,9 +529,10 @@ func (s *Server) startSingleMode() error {
 		result := locationEngine.Match(ctx.Path())
 		if result != nil && result.Handler != nil {
 			result.Handler(ctx)
+			matcher.ReleaseMatchResult(result)
 			return
 		}
-		// 无匹配，返回 404
+		matcher.ReleaseMatchResult(result)
 		ctx.SetStatusCode(404)
 		ctx.SetBodyString("Not Found")
 	}