refactor(errs): migrate from gperr.Error to standard Go error interface

This is a large-scale refactoring across the codebase that replaces the custom
`gperr.Error` type with Go's standard `error` interface. The changes include:

- Replacing `gperr.Error` return types with `error` in function signatures
- Using `errors.New()` and `fmt.Errorf()` instead of `gperr.New()` and `gperr.Errorf()`
- Using `%w` format verb for error wrapping instead of `.With()` method
- Replacing `gperr.Subject()` calls with `gperr.PrependSubject()`
- Converting error logging from `gperr.Log*()` functions to zerolog's `.Err().Msg()` pattern
- Update NewLogger to handle multiline error message
- Updating `goutils` submodule to latest commit

This refactoring aligns with Go idioms and removes the dependency on
custom error handling abstractions in favor of standard library patterns.

internal/net/gphttp/middleware/middleware_chain.go

@@ -2,6 +2,7 @@ package middleware
 
 import (
 	"net/http"
+	"strconv"
 
 	gperr "github.com/yusing/goutils/errs"
 )
@@ -47,7 +48,7 @@ func (m *middlewareChain) modifyResponse(resp *http.Response) error {
 	}
 	for i, mr := range m.modResps {
 		if err := mr.modifyResponse(resp); err != nil {
-			return gperr.Wrap(err).Subjectf("%d", i)
+			return gperr.PrependSubject(err, strconv.Itoa(i))
 		}
 	}
 	return nil