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/io.go

@@ -10,7 +10,6 @@ import (
 
 	"github.com/yusing/godoxy/internal/common"
 	"github.com/yusing/godoxy/internal/logging/accesslog"
-	gperr "github.com/yusing/goutils/errs"
 )
 
 type noopWriteCloser struct {
@@ -31,7 +30,7 @@ var (
 	testFilesLock sync.Mutex
 )
 
-func openFile(path string) (io.WriteCloser, gperr.Error) {
+func openFile(path string) (io.WriteCloser, error) {
 	switch path {
 	case "/dev/stdout":
 		return stdout, nil