Address ionite34 review feedback

- Add timestamp to .bak filenames (e.g. settings.json.20260408-020219.bak)
  to preserve original backup if corruption recurs
- Add try-catch around File.Move in SaveSettings/SaveSettingsAsync to
  clean up orphaned .tmp files if the move fails due to file locks

https://claude.ai/code/session_01Gej4ey7eUsbPRDqFWwxKyZ

Author: claude

StabilityMatrix.Core/Services/SettingsManager.cs

@@ -568,7 +568,8 @@ private void BackupCorruptedFile(byte[] rawBytes)
     {
         try
         {
-            var backupPath = SettingsFile + ".bak";
+            var timestamp = DateTime.Now.ToString("yyyyMMdd-HHmmss");
+            var backupPath = SettingsFile + $".{timestamp}.bak";
             File.WriteAllBytes(backupPath, rawBytes);
             logger.LogInformation("Backed up corrupted settings file to {BackupPath}", backupPath);
         }
@@ -614,7 +615,16 @@ protected virtual void SaveSettings(CancellationToken cancellationToken = defaul
             // Write to temp file then rename for atomic save
             var tempPath = SettingsFile + ".tmp";
             File.WriteAllBytes(tempPath, jsonBytes);
-            File.Move(tempPath, SettingsFile, overwrite: true);
+            try
+            {
+                File.Move(tempPath, SettingsFile, overwrite: true);
+            }
+            catch (Exception ex)
+            {
+                logger.LogWarning(ex, "Failed to move temp settings file, cleaning up");
+                try { File.Delete(tempPath); } catch { /* best effort */ }
+                throw;
+            }
         }
         finally
         {
@@ -658,7 +668,16 @@ protected virtual async Task SaveSettingsAsync(CancellationToken cancellationTok
             // Write to temp file then rename for atomic save
             var tempPath = SettingsFile + ".tmp";
             await File.WriteAllBytesAsync(tempPath, jsonBytes, cancellationToken).ConfigureAwait(false);
-            File.Move(tempPath, SettingsFile, overwrite: true);
+            try
+            {
+                File.Move(tempPath, SettingsFile, overwrite: true);
+            }
+            catch (Exception ex)
+            {
+                logger.LogWarning(ex, "Failed to move temp settings file, cleaning up");
+                try { File.Delete(tempPath); } catch { /* best effort */ }
+                throw;
+            }
         }
         finally
         {