ahci: scan all ports; fat: mount first valid FAT32 disk

The kernel previously started only AHCI port 0, so any launch where the
firmware/QEMU put something else on port 0 (e.g. the ESP from an implicit
-drive file=fat:rw:esp) left the real disk unnoticed: 'unsupported sector
size 0' and no mount.

- ahci.rs: enumerate CAP.NP/PI ports, start every port that links up
  (empty ports settle at DET=0 and are skipped quickly), keep up to 8
  disks, and expose disk_count()/select() for the filesystem
- fat.rs: try each disk in port order and mount the first valid FAT32
  volume; non-FAT disks are logged and skipped
- scripts/boot.sh: attach the data disk on ide.0 and the ESP on ide.1
  (DISK_IMG env var, default /tmp/disk.img), matching the Makefile
- Verified with the disk on port 0 (Makefile style), port 5 (old-style
  command line), and with the ESP on port 0; fsck.fat stays clean

1 files changed, 2 insertions, 2 deletions

diff --git a/scripts/qemu.sh b/scripts/qemu.sh
index 123d9d0..b8997ba 100755
--- a/scripts/qemu.sh
+++ b/scripts/qemu.sh
@@ -41,8 +41,8 @@ while [ $# -gt 0 ]; do
         --image | -i)
                 _img_file="$(printf -- '-drive file=%s,format=raw,if=none,id=hd' "$2")"
                 # Explicit buses: data disk -> ide.0 (port 0), ESP -> ide.1.
-                DRIVE_ARGS=("$_img_file" '-device' 'ide-hd,drive=hd,bus=ide.0' \
-                        '-drive' 'file=fat:rw:esp,format=raw,if=none,id=esp' \
+                DRIVE_ARGS=("$_img_file" '-device' 'ide-hd,drive=hd,bus=ide.0'
+                        '-drive' 'file=fat:rw:esp,format=raw,if=none,id=esp'
                         '-device' 'ide-hd,drive=esp,bus=ide.1')
                 shift 2
                 ;;