feat(merge): toggle add/remove per side, MAIN/INCOMING labels, files readout

- Conflict accept is now a per-side toggle: > adds MAIN (ours), < adds INCOMING
  (theirs) in click order (first on top); clicking again removes that side, so each
  side is included at most once. Region content is rebuilt from the included set.
- Drop the separate reset (x) control — toggling both off clears the region.
- Relabel the panes/tooltips Ours/Theirs -> MAIN/INCOMING (merge target vs task).
- Add a cross-file 'N of M files unresolved' readout (FilesSummary) so you can see
  how many more files still have conflicts. en/de updated; Ui 128 + Loc 16 green.

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

@@ -88,6 +88,21 @@ public sealed partial class ConflictResolverViewModel : ObservableObject
     public IReadOnlyList<string> BinaryFilePaths => Files.Where(f => f.IsBinary).Select(f => f.Path).ToList();
     public bool HasBinaryFiles => Files.Any(f => f.IsBinary);
 
+    public bool HasMultipleFiles => Files.Count > 1;
+
+    /// <summary>Cross-file progress shown in the editor: how many files still have unresolved
+    /// (or binary) conflicts, so you can see how many more need attention.</summary>
+    public string FilesSummary
+    {
+        get
+        {
+            var total = Files.Count;
+            if (total == 0) return "";
+            var unresolved = Files.Count(f => !f.AllResolved);
+            return unresolved == 0 ? $"All {total} files resolved" : $"{unresolved} of {total} files unresolved";
+        }
+    }
+
     public string ContinueHint => HasBinaryFiles
         ? "Binary conflicts must be resolved externally — abort and resolve in your editor."
         : "";
@@ -171,6 +186,8 @@ public sealed partial class ConflictResolverViewModel : ObservableObject
         OnPropertyChanged(nameof(TotalConflicts));
         OnPropertyChanged(nameof(BinaryFilePaths));
         OnPropertyChanged(nameof(HasBinaryFiles));
+        OnPropertyChanged(nameof(HasMultipleFiles));
+        OnPropertyChanged(nameof(FilesSummary));
         RecomputeCanContinue();
         if (_flat.Count > 0)
             MoveTo(0); // also sets ActiveFile via MoveTo
@@ -193,6 +210,7 @@ public sealed partial class ConflictResolverViewModel : ObservableObject
             OnPropertyChanged(nameof(ResolvedCount));
             OnPropertyChanged(nameof(PositionText));
             OnPropertyChanged(nameof(ActiveResultText));
+            OnPropertyChanged(nameof(FilesSummary));
         }
     }