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/route/rules/do_log_test.go

@@ -12,7 +12,6 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/yusing/godoxy/internal/serialization"
-	gperr "github.com/yusing/goutils/errs"
 )
 
 // mockUpstream creates a simple upstream handler for testing
@@ -32,7 +31,7 @@ func mockUpstreamWithHeaders(status int, body string, headers http.Header) http.
 	}
 }
 
-func parseRules(data string, target *Rules) gperr.Error {
+func parseRules(data string, target *Rules) error {
 	_, err := serialization.ConvertString(data, reflect.ValueOf(target))
 	return err
 }