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/maxmind/README.md

@@ -99,7 +99,7 @@ type Location struct {
 
 ```go
 // LoadMaxMindDB loads or downloads the MaxMind database.
-func (cfg *MaxMind) LoadMaxMindDB(parent task.Parent) gperr.Error
+func (cfg *MaxMind) LoadMaxMindDB(parent task.Parent) error
 ```
 
 ### Lookup
@@ -324,8 +324,8 @@ The maxmind package integrates with:
 
 ```go
 var (
-    ErrResponseNotOK   = gperr.New("response not OK")
-    ErrDownloadFailure = gperr.New("download failure")
+    ErrResponseNotOK   = errors.New("response not OK")
+    ErrDownloadFailure = errors.New("download failure")
 )
 ```