feat(rust): Implement Rust-for-SUB-OS kernel layer, ChaCha20 crypto, HWMON thermal governor, and lazybox applets

- Add freestanding no_std Rust kernel layer compiled with rustc
- Implement memory-safe ChaCha20 RFC-8439 stream cipher and CSPRNG in Rust
- Implement intelligent thermal fan speed governor in Rust
- Add printk macro bridge (kprint!, kprintln!) for Rust
- Register 'rustinfo' and 'chacha20' LazyBox applets
- Enable x86_64 hardware FPU & SSE (CR4.OSFXSR/OSXMMEXCPT)
- Add cross-architecture C-bridge for ARM targets
- Update stage2.asm kernel sector copy bounds to 448 KB

include/kernel/rust.h

@@ -0,0 +1,20 @@
+#ifndef _KERNEL_RUST_H
+#define _KERNEL_RUST_H
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+
+typedef struct {
+    uint32_t target_fan_rpm;
+    uint8_t throttle_level;
+    bool is_critical;
+} __attribute__((packed)) rust_thermal_report_t;
+
+int rust_kernel_init(void);
+const char* rust_kernel_status(void);
+int rust_chacha20_crypt(const uint8_t* key, const uint8_t* nonce, uint32_t counter, uint8_t* data, size_t len);
+int rust_csprng_get_random(uint8_t* buffer, size_t len);
+rust_thermal_report_t rust_sensor_calc_fan_curve(int32_t temp_celsius);
+
+#endif // _KERNEL_RUST_H