x16-PRos v0.9

A big release focused on program formats, large-file I/O, fresh system tooling, and a much more capable SETUP

The most important changes:

MZ EXE program support. You can run some MS-DOS games or programs in .EXE format.
SETUP can now install x16-PRos to any disk. Pick your target drive (floppy / HDD / SSD) and SETUP formats it and lays down the system files for you
Installs are no longer capped at 1.44 MB. HDD/SSD partitions can be much larger, leaving real room for files and programs
Improved HDD / multi-disk handling
Seven new terminal themes, selectable via the THEME program
New SETTINGS.BIN program - place to configure username, timezone and more
New CALENDAR.BIN program
CPU utility is now a stand-alone as CPU.BIN instead of being baked into the kernel
PAINT.BIN update: save your drawing to a file, plus new line-drawing mode (toggle between free and line with TAB)
Mouse text selection in the terminal (bare-bones, but it's there)
Default prompt config fix

PLE (PRos Large Executable) - new native format. Hybrid of .BIN and MZ EXE: multi-segment, files up to ~448 KB, built-in description / author metadata, and a built-in 64×64 splash logo shown before the program runs.
New build tool scripts/img2pleimg.py converts any image (PNG/JPG/etc.) to a 4096-byte PLE logo, snapped to the EGA 16-color palette
New syscall INT 0x22 AH=0x13 - write huge file from arbitrary segment:offset, supports files larger than 64 KB
New syscalls INT 0x21 AH=0x0C (clear screen + reapply current theme) and AH=0x06 (clear screen, default VGA)
Improved mouse driver

.BIN program and CFG buffers moved out of the kernel segment (now at 0x1000 instead of 0x2000), leaving more room for the kernel itself
Various bugfixes