Preserve best-effort token clear behavior

Keep DeviceIdentityStore.ClearStoredTokens as a best-effort operation by logging unexpected failures from the shared atomic token-clear helper instead of allowing them to escape connection cleanup flows.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Christine Yan

src/OpenClaw.Connection/DeviceIdentityStore.cs

@@ -39,6 +39,13 @@ public void StoreToken(string identityPath, string token, string[]? scopes, stri
     /// </summary>
     public static void ClearStoredTokens(string identityDir, IOpenClawLogger? logger = null)
     {
-        DeviceIdentity.TryClearAllDeviceTokens(identityDir, logger);
+        try
+        {
+            DeviceIdentity.TryClearAllDeviceTokens(identityDir, logger);
+        }
+        catch (Exception ex)
+        {
+            logger?.Warn($"[IdentityStore] Failed to clear device tokens: {ex.Message}");
+        }
     }
 }