* **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.