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/Simulator.cpp

@@ -17,7 +17,7 @@ static bool initBoot() {
     return true;
 }
 
-TT_UNUSED static void deinitPower() {
+static void deinitPower() {
     lvgl_task_interrupt();
     while (lvgl_task_is_running()) {
         tt::kernel::delayMillis(10);