perf: optimize MQTT logging with string pre-allocation (#93)

* Initial plan

* perf: optimize millis64, component loop, and MQTT logging

Co-authored-by: cziter15 <[email protected]>

* perf: revert millis64 lazy-eval to pre-update approach

Co-authored-by: cziter15 <[email protected]>

* perf: improve branch prediction by hinting on component state

Co-authored-by: cziter15 <[email protected]>

* perf: remove __builtin_expect as ESP has no branch prediction

Co-authored-by: cziter15 <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: cziter15 <[email protected]>

Author: Copilot

src/ksf/comp/ksMqttConnector.cpp

@@ -119,6 +119,7 @@ namespace ksf::comps
 
 #ifdef APP_LOG_ENABLED
 		app->log([&](std::string& out) {
+			out.reserve(64 + topicStr.length() + payloadStr.length());
 			out += PSTR("[ MqttConnector ] Received on topic: ");
 			out += topicStr;
 			out += PSTR(", value: ");