fix(route): Add fullPath in context copy (#3784)

* fix: Add fullPath in context copy

* Update context.go

---------

Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>

context.go

@@ -120,6 +120,7 @@ func (c *Context) Copy() *Context {
 	cp.Writer = &cp.writermem
 	cp.index = abortIndex
 	cp.handlers = nil
+	cp.fullPath = c.fullPath
 
 	cKeys := c.Keys
 	cp.Keys = make(map[string]any, len(cKeys))