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.

Tests/Tactility/CMakeLists.txt

@@ -21,7 +21,7 @@ add_test(NAME TactilityTests
 target_link_libraries(TactilityTests PRIVATE
     Tactility
     TactilityCore
-    Tactility
+    TactilityKernel
     Simulator
     SDL2::SDL2-static SDL2-static
 )

Tests/TactilityCore/CMakeLists.txt

@@ -20,6 +20,7 @@ add_test(NAME TactilityCoreTests
 
 target_link_libraries(TactilityCoreTests PUBLIC
     TactilityCore
+    TactilityKernel
     TactilityFreeRtos
     freertos_kernel
 )

Tests/TactilityKernel/TimeAndDelay.cpp

@@ -0,0 +1,30 @@
+#include "doctest.h"
+#include <Tactility/Time.h>
+#include <Tactility/Delay.h>
+
+TEST_CASE("delay ticks should be accurate within 1 tick") {
+    auto start_time = get_ticks();
+    delay_ticks(100);
+    auto end_time = get_ticks();
+    auto difference = end_time - start_time;
+    CHECK_EQ(difference >= 100, true);
+    CHECK_EQ(difference <= 101, true);
+}
+
+TEST_CASE("delay millis should be accurate within 1 tick") {
+    auto start_time = get_millis();
+    delay_millis(100);
+    auto end_time = get_millis();
+    auto difference = end_time - start_time;
+    CHECK_EQ(difference >= 100, true);
+    CHECK_EQ(difference <= 101, true);
+}
+
+TEST_CASE("microsecond time should be accurate within 1 tick") {
+    auto start_time = get_micros_since_boot();
+    delay_millis(100);
+    auto end_time = get_micros_since_boot();
+    auto difference = (end_time - start_time) / 1000;
+    CHECK_EQ(difference >= 99, true);
+    CHECK_EQ(difference <= 101, true);
+}