Bugfix/10 console poll heap pressure

[LK-Simon]

Summary

Fixes a low-memory failure path in Console::Poll() discovered during ESP32 EventConsole-Lab stress testing.

Closes #10.

Problem

ConsoleConfig::MaximumLineLength bounds Console input, but the backing std::string previously grew incrementally from Console::Poll().

Under severe heap pressure, a normal std::string::push_back() could therefore require a late allocation and ultimately reach std::terminate() if memory was unavailable.

The observed ESP32 backtrace resolved through:

std::terminate
operator new
std::string::_M_create
std::string::_M_mutate
std::string::push_back
ESPressio::Serial::Console::Poll