Add full automotive RTOS project

Add kernel (Cortex-M0/M3/M4, Tricore, S32K, RISC-V ports), drivers,
middleware (CAN stack, diagnostics, safety), applications, board
support, build/test tooling, and documentation.

kernel/include/mutex.h

@@ -0,0 +1,28 @@
+/**
+ * @file mutex.h
+ * @brief Mutex with priority inheritance
+ */
+
+#ifndef MUTEX_H
+#define MUTEX_H
+
+#include "kernel.h"
+
+/* Mutex Control Block */
+typedef struct {
+    TaskHandle_t owner;
+    TaskPriority_t original_priority;
+    uint32_t lock_count;
+    TaskHandle_t* waiting_tasks;
+    uint32_t waiting_count;
+    bool recursive;
+} Mutex_t;
+
+/* Mutex Functions */
+KernelStatus_t mutex_create(Mutex_t* mutex, bool recursive);
+KernelStatus_t mutex_lock(Mutex_t* mutex, TimeOut_t timeout);
+KernelStatus_t mutex_unlock(Mutex_t* mutex);
+KernelStatus_t mutex_delete(Mutex_t* mutex);
+TaskHandle_t mutex_get_owner(Mutex_t* mutex);
+
+#endif /* MUTEX_H */