fix(merge): unresolved conflicts compose to empty, not Ours (+ review nits)

Code-review follow-ups before push:
- MergeFile.ResultText/Compose() fell back to Ours for unresolved conflicts while
  the editor seeds them empty — align both on empty so the public model matches the
  pane and Continue can't silently auto-accept Ours.
- Bound the gutter re-layout retry (was an unbounded Background re-post when the
  editor isn't laid out, e.g. minimized).
- Pluralize the readout ('1 conflict' not '1 conflicts'). Tests updated. Ui 128 green.

src/ClaudeDo.Ui/ViewModels/Conflicts/ConflictModels.cs

@@ -72,9 +72,11 @@ public sealed class MergeFile
     /// <summary>A binary file can't be resolved in-app; a text file is done once every block is resolved.</summary>
     public bool AllResolved => !IsBinary && Conflicts.All(c => c.IsResolved);
 
-    /// <summary>Reassemble the file: stable text verbatim, each conflict replaced by its resolution.</summary>
+    /// <summary>Reassemble the file: stable text verbatim, each conflict replaced by its resolution
+    /// (empty when unresolved — the same "empty start" the editor shows; Continue is gated on
+    /// <see cref="AllResolved"/> so an unresolved conflict never actually reaches here).</summary>
     public string Compose() => string.Concat(
-        Segments.Select(s => s.IsConflict ? (s.Conflict!.Resolution ?? s.Conflict.Ours) : s.StableText));
+        Segments.Select(s => s.IsConflict ? (s.Conflict!.Resolution ?? "") : s.StableText));
 
     /// <summary>Left pane document: stable regions verbatim, conflict regions show Ours text.</summary>
     public string OursText => string.Concat(
@@ -84,7 +86,8 @@ public sealed class MergeFile
     public string TheirsText => string.Concat(
         Segments.Select(s => s.IsConflict ? s.Conflict!.Theirs : s.StableText));
 
-    /// <summary>Middle (result) pane document: stable regions verbatim, conflict regions show Resolution if set, else Ours.</summary>
+    /// <summary>Middle (result) pane document: stable regions verbatim, conflict regions show the
+    /// chosen Resolution, or empty when unresolved (the editor builds each conflict up from empty).</summary>
     public string ResultText => string.Concat(
-        Segments.Select(s => s.IsConflict ? (s.Conflict!.Resolution ?? s.Conflict.Ours) : s.StableText));
+        Segments.Select(s => s.IsConflict ? (s.Conflict!.Resolution ?? "") : s.StableText));
 }

src/ClaudeDo.Ui/ViewModels/Conflicts/ConflictResolverViewModel.cs

@@ -81,7 +81,7 @@ public sealed partial class ConflictResolverViewModel : ObservableObject
             if (ActiveFile is null || ActiveFile.Conflicts.Count == 0) return "No text conflicts";
             var count = ActiveFile.Conflicts.Count;
             var resolved = ActiveFile.Conflicts.Count(c => c.IsResolved);
-            return $"{count} conflicts · {resolved} resolved";
+            return $"{count} {(count == 1 ? "conflict" : "conflicts")} · {resolved} resolved";
         }
     }