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.

TactilityKernel/Source/Log.cpp

@@ -7,6 +7,8 @@
 #include <stdio.h>
 #include <stdarg.h>
 
+extern "C" {
+
 void log_generic(const char* tag, const char* format, ...) {
     va_list args;
     va_start(args, format);
@@ -16,4 +18,6 @@ void log_generic(const char* tag, const char* format, ...) {
     va_end(args);
 }
 
+}
+
 #endif