feat: publish FreeRTOS C FC02 card

tests/context_contract.c

@@ -0,0 +1,14 @@
+#include <stddef.h>
+
+#include "task01_first_task.h"
+
+_Static_assert( offsetof( WorkerContext, id ) == 0U,
+                "worker id must be the first debugger-visible field" );
+_Static_assert( sizeof( ( ( WorkerContext * ) 0 )->handle ) == sizeof( TaskHandle_t ),
+                "the public handle must retain the FreeRTOS ABI type" );
+
+/* Deliberately unsafe compile-only exhibit: C accepts this wrong cast. */
+WorkerContext * task01_wrong_context_cast_exhibit( void * supervisor )
+{
+    return ( WorkerContext * ) supervisor;
+}