Fix Arduino String .size() → .length() in hmac.cpp (pre-existing bug surfaced by compilation). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Fix Arduino String .size() → .length() in hmac.cpp (pre-existing bug surfaced by compilation). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>