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/keyboard/KeyboardSettings.cpp

@@ -170,7 +170,7 @@ public:
         }
     }
 
-    void onHide(TT_UNUSED AppContext& app) override {
+    void onHide(AppContext& app) override {
         if (updated) {
             const auto copy = kbSettings;
             getMainDispatcher().dispatch([copy]{ settings::keyboard::save(copy); });