Stop failing sync over already-sent campaigns still in the repo

A campaign.md is meant to stay around after it's sent as a record of what
went out and when. Treating any non-draft campaign as a hard rejection
forced deleting it just to keep CI green, and there was no way to fail on
resolving a stale list/attachment reference either -- an archived
campaign has nothing left to resolve, so check status before doing any of
that work. Non-draft campaigns now report as a distinct, non-error
"skipped" bucket instead of "rejected".

internal/campaign/sync.go

@@ -18,7 +18,8 @@ import (
 type SyncResult struct {
 	Synced        []string // created or updated (content changed) in listmonk
 	Unchanged     []string // existing draft, content identical — no API write, no preview
-	Rejected      []string // validation/segmentation/list-lookup failure, or non-draft in listmonk — nothing written
+	Skipped       []string // already sent/running/paused/etc. in listmonk — a historical record, left untouched, not an error
+	Rejected      []string // validation/segmentation/list-lookup failure — nothing written
 	PreviewFailed []string // content synced fine, but the automatic preview send itself failed
 }
 
@@ -45,6 +46,10 @@ func SyncDir(lm *listmonk.Client, root string, defaultPreviewEmails []string) (*
 			result.Rejected = append(result.Rejected, fmt.Sprintf("%s: %v", slug, err))
 			continue
 		}
+		if res.Skipped != "" {
+			result.Skipped = append(result.Skipped, fmt.Sprintf("%s: %s", slug, res.Skipped))
+			continue
+		}
 		if !res.Changed {
 			result.Unchanged = append(result.Unchanged, slug)
 			continue
@@ -59,7 +64,8 @@ func SyncDir(lm *listmonk.Client, root string, defaultPreviewEmails []string) (*
 
 type syncOneResult struct {
 	Changed    bool
-	PreviewErr error // set only when Changed and the automatic preview send failed
+	Skipped    string // non-empty (the listmonk status) when left untouched because it's no longer a draft
+	PreviewErr error  // set only when Changed and the automatic preview send failed
 }
 
 func syncOne(lm *listmonk.Client, slug, dir, path string, defaultPreviewEmails []string) (syncOneResult, error) {
@@ -68,6 +74,22 @@ func syncOne(lm *listmonk.Client, slug, dir, path string, defaultPreviewEmails [
 		return syncOneResult{}, err
 	}
 
+	existing, err := lm.FindCampaignByName(slug)
+	if err != nil {
+		return syncOneResult{}, err
+	}
+	if existing != nil && existing.Status != "draft" {
+		// Once a campaign has actually gone out (or is running/paused/etc.),
+		// its campaign.md is a historical record of what was sent and when —
+		// not something sync should touch or fail the build over. Forcing it
+		// to be deleted just to keep CI green would throw away exactly the
+		// record someone would want to look back at later. Check this before
+		// resolving anything else below, so a since-renamed list or a
+		// since-changed attachment on an old campaign can never break the
+		// build either — an archived campaign has nothing left to resolve.
+		return syncOneResult{Skipped: existing.Status}, nil
+	}
+
 	listIDs, err := resolveLists(lm, fm.Lists)
 	if err != nil {
 		return syncOneResult{}, err
@@ -97,11 +119,6 @@ func syncOne(lm *listmonk.Client, slug, dir, path string, defaultPreviewEmails [
 		MediaIDs:   mediaIDs,
 	}
 
-	existing, err := lm.FindCampaignByName(slug)
-	if err != nil {
-		return syncOneResult{}, err
-	}
-
 	var campaignID int
 	var changed bool
 	switch {
@@ -112,11 +129,6 @@ func syncOne(lm *listmonk.Client, slug, dir, path string, defaultPreviewEmails [
 		}
 		campaignID, changed = created.ID, true
 
-	case existing.Status != "draft":
-		// The core safety invariant: never silently skip or overwrite a
-		// live/sent campaign. This is a hard rejection, not a warning.
-		return syncOneResult{}, fmt.Errorf("campaign is %s in listmonk; sync refuses to modify a non-draft campaign", existing.Status)
-
 	case campaignUnchanged(existing, input):
 		campaignID, changed = existing.ID, false