feat(kernel): add PL011 UART console and arch I/O helpers

- Add IOSerial: PL011 (0x0900_0000) TX with FIFO-full polling, yield while waiting
- Add Arch/IO.h (32-bit MMIO with DSB) and Arch/CPU.h (yield, WFI)
- Extend types.h (e.g. ASCII, Address, Int/UInt aliases)
- Wire KernelMain to IOSerialPutString for early boot output
- Drop .sourcekit-lsp config; note IO glob in CMake (commented)

Kernel/Include/Arch/CPU.h

@@ -0,0 +1,9 @@
+#pragma once
+
+static inline void CPUYield() {
+    __asm__ volatile ("yield" ::: "memory");
+}
+
+static inline void CPUWaitForInterrupt() {
+    __asm__ volatile ("wfi" ::: "memory");
+}