feat(arch): Add armv8i (32-bit ARM/AArch32) architecture & complete TUI configurator

- Support ARMv8i / ARM32 (AArch32) baremetal target with arm-linux-gnueabihf toolchain
- Implement ARMv8i boot entry point, banked exception mode stacks (IRQ, ABT, UND, SVC)
- Implement 8 exception vectors, GICv2 distributor/CPU interface, CP15 Generic Timer (100 Hz), flat Section MMU
- Support PL011 UART for early console & interactive LazyBox TTY input
- Update Makefile with make armv8i_defconfig and automated cross-compilation
- Update scripts/kconfig/menuconfig.py with dedicated armv8i options

include/arch/armv8i/uart.h

@@ -0,0 +1,24 @@
+#ifndef _ARCH_ARMV8I_UART_H
+#define _ARCH_ARMV8I_UART_H
+
+#include <stdint.h>
+
+#define PL011_UART0_BASE 0x09000000
+
+#define UARTDR   0x000
+#define UARTRSR  0x004
+#define UARTFR   0x018
+#define UARTCR   0x030
+#define UARTIMSC 0x038
+#define UARTICR  0x044
+
+#define UARTFR_TXFF (1 << 5)
+#define UARTFR_RXFE (1 << 4)
+
+void uart_pl011_init(void);
+void uart_pl011_putc(char c);
+void uart_pl011_puts(const char* str);
+char uart_pl011_getc(void);
+int  uart_pl011_has_data(void);
+
+#endif // _ARCH_ARMV8I_UART_H