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.

Drivers/RgbDisplay/Source/RgbDisplay.cpp

@@ -12,9 +12,10 @@
 static const auto LOGGER = tt::Logger("RgbDisplay");
 
 RgbDisplay::~RgbDisplay() {
-    if (displayDriver != nullptr && displayDriver.use_count() > 1) {
-        tt_crash("DisplayDriver is still in use. This will cause memory access violations.");
-    }
+    check(
+        displayDriver == nullptr || displayDriver.use_count() == 0,
+        "DisplayDriver is still in use. This will cause memory access violations."
+    );
 }
 
 bool RgbDisplay::start() {