Translate IsMain in SubmitUpdatePublication after rebasing onto develop

develop's #2367 rerouted PublicationSync through the new no-re-read
SubmitUpdatePublication (so sync tolerates a publication deleted on the
other side). That override applied the raw patch, so once the IsMain
feature rebased on top, the sync path set IsMain as a plain LWW field
and skipped the converging SetMainPublicationChange. Move the IsMain
translation into SubmitUpdatePublication so every update path converges;
UpdatePublication now just submits and re-reads, matching the
SubmitUpdate*/Update* pattern develop uses for the other entity types.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: myieye

backend/FwLite/LcmCrdt/CrdtMiniLcmApi.cs

@@ -187,30 +187,28 @@ public async Task<Publication> CreatePublication(Publication pub)
 
     public async Task SubmitUpdatePublication(Guid id, UpdateObjectInput<Publication> update)
     {
-        await AddChanges(update.Patch.ToChanges(id));
-    }
-
-    public async Task<Publication> UpdatePublication(Guid id, UpdateObjectInput<Publication> update)
-    {
-        await using var repo = await repoFactory.CreateRepoAsync();
-        var pub = await repo.GetPublication(id) ?? throw NotFoundException.ForType<Publication>(id);
-
         // IsMain is applied via SetMainPublicationChange (which converges), not as a plain field patch, so it's
         // stripped from the patch and translated to that change — but only when an IsMain op is actually present.
         if (update.TryGetPropertyChange<Publication, bool>(nameof(Publication.IsMain), out var isMain))
         {
             var patch = new JsonPatchDocument<Publication>();
             patch.Operations.AddRange(update.Patch.Operations.Where(op =>
                 !string.Equals(op.Path, $"/{nameof(Publication.IsMain)}", StringComparison.OrdinalIgnoreCase)));
-            var changes = patch.ToChanges(pub.Id).ToList();
+            var changes = patch.ToChanges(id).ToList();
             // prior/wrapping validation actually prevents setting IsMain to false via patch, so isMain is always true
-            if (isMain) changes.Add(new SetMainPublicationChange(pub.Id));
+            if (isMain) changes.Add(new SetMainPublicationChange(id));
             if (changes.Count > 0) await AddChanges(changes);
         }
         else if (update.Patch.Operations.Count > 0)
         {
-            await AddChanges(update.Patch.ToChanges(pub.Id));
+            await AddChanges(update.Patch.ToChanges(id));
         }
+    }
+
+    public async Task<Publication> UpdatePublication(Guid id, UpdateObjectInput<Publication> update)
+    {
+        await SubmitUpdatePublication(id, update);
+        await using var repo = await repoFactory.CreateRepoAsync();
         return await repo.GetPublication(id) ?? throw NotFoundException.ForType<Publication>($"{id} (invalid patching to a new id?)");
     }