Symbol loading from ELF, AHCI/ATA PCI probing, PTY VMIN/VTIME
* Replace nm sym.map symbol loader with direct ELF section parsing;
load_symbols() reads .symtab/.dynsym from the kernel ELF on disk,
drop libs/parse/sym.c and the nm/SYMBOL_MAP build targets
* Overhaul AHCI controller discovery: scan SATA/RAID/ATA PCI
subclasses, decode 64-bit BARs, accept sig==0 ports, add fallback
port selection, validate HBA cap before use
* Add PCI IDE probing to ATA: read BAR0-3 for native-mode channels,
enable bus mastering; ata_probe_channel gains use_irq parameter;
fall back to legacy IO ports if no PCI IDE found
* Implement _queue_read_termios() in pty.c with POSIX VMIN/VTIME
raw-mode semantics; slave reads use it instead of plain _queue_read
* Add vi frame cache: build each row into a fixed buffer and only emit
escape sequences for rows that changed; EINTR loop fix in read_key