build: the libavr pin advances past phase 6

The renames land (interrupt_guard, consume_reset_cause, set_duty), the
sampler binds its input in the new converter shape (the input pack plus
in<>::start() as free-running's one kick), and the console states
.allow_baud_error = true for the 115200-at-16-MHz this board has always
spoken - the receiver-tolerance table libavr now enforces is stricter
than the rate's own +2.1 %. The loader probe reads through
avr::flash_load instead of raw pgmspace, the terminal's line buffer is
std::array with backspace and delete named, the tree is reformatted
under InsertBraces, and the sources are ASCII.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/main.cpp

@@ -16,14 +16,15 @@ int main()
 
 	avr::init<uptime::ticker, sampler::input, fan, serial_t, statistics>();
 	avr::irq::enable();
-	sampler::input::start();
+	sampler::thermistor::start();
 	controller::init();
 	terminal::init();
 
 	while (true) {
 		controller::poll();
-		if (controller::data_available())
+		if (controller::data_available()) {
 			statistics::record(static_cast<std::int8_t>((controller::temperature_quarters() + 2) / 4));
+		}
 		terminal::poll();
 	}
 }