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/isr.h

@@ -0,0 +1,36 @@
+/**
+ * @file isr.h
+ * @brief Interrupt Service Routine management
+ */
+
+#ifndef ISR_H
+#define ISR_H
+
+#include "kernel.h"
+
+/* ISR Types */
+typedef void (*ISRHandler_t)(void);
+
+/* ISR Configuration */
+typedef struct {
+    uint32_t irq_number;
+    ISRHandler_t handler;
+    uint8_t priority;
+} ISRConfig_t;
+
+/* ISR Functions */
+KernelStatus_t isr_register(uint32_t irq_number, ISRHandler_t handler,
+                           uint8_t priority);
+KernelStatus_t isr_unregister(uint32_t irq_number);
+KernelStatus_t isr_enable(uint32_t irq_number);
+KernelStatus_t isr_disable(uint32_t irq_number);
+KernelStatus_t isr_set_priority(uint32_t irq_number, uint8_t priority);
+void isr_enter(void);
+void isr_exit(void);
+bool isr_is_in_context(void);
+
+/* Critical Section Management */
+void critical_section_enter(void);
+void critical_section_exit(void);
+
+#endif /* ISR_H */