ci: actually add the Padding suppression to .clang-tidy

The previous commit added the rationale comment but the disable
line itself didn't get written.  Add it.

Co-Authored-By: Claude Opus 4.7 <[email protected]>

Author: JoeMatt

.clang-tidy

@@ -27,6 +27,7 @@ Checks: >
   -bugprone-incorrect-roundings,
   -bugprone-multi-level-implicit-pointer-conversion,
   -clang-analyzer-deadcode.DeadStores,
+  -clang-analyzer-optin.performance.Padding,
   -clang-analyzer-optin.portability.UnixAPI,
   -clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling,
   -clang-analyzer-valist.Uninitialized