fix: plug memory map leak, save sp_el0, dynamic UART, kill loop

- Bootloader: reallocate memory map buffer when ExitBootServices fails,
  so GetMemoryMap doesn't scribble past the old allocation on retry.
- vectors.S: actually store sp_el0 into the exception frame. Previously
  it was read into x24 and then… vanished. EL0 tasks would wake up with
  a corrupted stack pointer. Not great.
- Serial: split hardcoded 0x09000000 into a fallback default; add
  SerialUpdate() so the DTB-parsed UART address actually gets used.
- DTB: add bounds check on reserved[] with PMM's 3 extra slots accounted
  for, so malformed/overstuffed DTBs don't silently corrupt memory.
- PMM.h: bump kVMMaxReservedRegions 128→256, define kPMMReservedRegionCount.
- Types.h: remove `#define loop while(1)`. while(true) is fine.
- Rename IOSerial* → Serial* — the IO prefix was redundant, Serial.c
  already lives under IO/.

Kernel/Source/OS/Scheduler.c

@@ -85,11 +85,11 @@ Address SchedulerNext(Address stackPointer) {
         if (taskIterator->sleepTicks > 0) taskIterator->sleepTicks--;
         taskIterator = taskIterator->next;
     } while (taskIterator != gOSSchedulerCurrentTask->next);
-    
+
     if (gOSSchedulerCurrentTask->sleepTicks > 0) gOSSchedulerCurrentTask->sleepTicks--;
 
     OSTask* nextTask = gOSSchedulerCurrentTask->next;
-    loop {
+    while (true) {
         if (nextTask->state == OSTaskStateDead) {
             nextTask = nextTask->next;
             if (nextTask == gOSSchedulerCurrentTask) OSPanic("No running tasks");
@@ -110,7 +110,7 @@ Address SchedulerNext(Address stackPointer) {
         CPUSwitchAddressSpace(physicalL0Table);
     }
     gOSSchedulerCurrentTask = nextTask;
-    
+
     return gOSSchedulerCurrentTask->stackPointer;
 }
 
@@ -118,4 +118,4 @@ void SchedulerYield(UInt64 ticks) {
     gOSSchedulerCurrentTask->sleepTicks = ticks;
     gOSSchedulerCurrentTask->state = OSTaskStateSleeping;
     CPUException(kOSSchedulerExceptionNumber);
-}
+}