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/common.go

@@ -2,16 +2,16 @@ package route
 
 import (
 	"context"
+	"fmt"
 
 	entrypoint "github.com/yusing/godoxy/internal/entrypoint/types"
 	"github.com/yusing/godoxy/internal/types"
-	gperr "github.com/yusing/goutils/errs"
 )
 
 // checkExists checks if the route already exists in the entrypoint.
 //
 // Context must be passed from the parent task that carries the entrypoint value.
-func checkExists(ctx context.Context, r types.Route) gperr.Error {
+func checkExists(ctx context.Context, r types.Route) error {
 	if r.UseLoadBalance() { // skip checking for load balanced routes
 		return nil
 	}
@@ -26,7 +26,7 @@ func checkExists(ctx context.Context, r types.Route) gperr.Error {
 		existing, ok = entrypoint.FromCtx(ctx).StreamRoutes().Get(r.Key())
 	}
 	if ok {
-		return gperr.Errorf("route already exists: from provider %s and %s", existing.ProviderName(), r.ProviderName())
+		return fmt.Errorf("route already exists: from provider %s and %s", existing.ProviderName(), r.ProviderName())
 	}
 	return nil
 }