Various improvements (#461)

* **New Features**
  * Time and delay utilities added (ticks, ms, µs); SD card now uses an expansion-header CS pin; HTTP downloads warn when run on the GUI task and yield to avoid blocking.

* **Bug Fixes / Reliability**
  * Many hard-crash paths converted to guarded checks to reduce abrupt termination and improve stability.

* **Tests**
  * Unit tests added to validate time and delay accuracy.

* **Chores**
  * License header and build/macro updates.

Devices/simulator/Source/Main.cpp

@@ -15,7 +15,7 @@ void setMain(MainFunction newMainFunction) {
     mainFunction = newMainFunction;
 }
 
-static void freertosMainTask(TT_UNUSED void* parameter) {
+static void freertosMainTask(void* parameter) {
     LOGGER.info("starting app_main()");
     assert(simulator::mainFunction);
     mainFunction();