Express campaign client errors in the service layer

Remove status-to-error helpers and map loaded campaign data to
accessreview sentinels at each business rule instead of wrapping
coredata status values.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/accessreview/errors_test.go

@@ -1,50 +0,0 @@
-// Copyright (c) 2026 Probo Inc <hello@probo.com>.
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-// SOFTWARE.
-
-package accessreview
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"go.probo.inc/probo/pkg/coredata"
-)
-
-func TestCampaignNotDraftError(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		status coredata.AccessReviewCampaignStatus
-		want   error
-	}{
-		{status: coredata.AccessReviewCampaignStatusInProgress, want: ErrCampaignInProgress},
-		{status: coredata.AccessReviewCampaignStatusPendingActions, want: ErrCampaignPendingActions},
-		{status: coredata.AccessReviewCampaignStatusCompleted, want: ErrCampaignCompleted},
-		{status: coredata.AccessReviewCampaignStatusCancelled, want: ErrCampaignCancelled},
-	}
-
-	for _, tt := range tests {
-		t.Run(string(tt.status), func(t *testing.T) {
-			t.Parallel()
-
-			assert.ErrorIs(t, campaignNotDraftError(tt.status), tt.want)
-		})
-	}
-}