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.

Tactility/Source/app/i2cscanner/I2cScanner.cpp

@@ -325,7 +325,7 @@ void I2cScannerApp::selectBus(int32_t selected) {
     updateViews();
 }
 
-void I2cScannerApp::onPressScan(TT_UNUSED lv_event_t* event) {
+void I2cScannerApp::onPressScan(lv_event_t* event) {
     if (scanState == ScanStateScanning) {
         stopScanning();
     } else {