fat: mount every FAT32 volume under /disk/<UID>/, fix multi-entry LFN

- fat.rs: VOL: Option<Volume> → VOLS: Vec<Volume>; try_mount() returns
  a Volume per disk and init() mounts every valid FAT32 volume found.
  Volume UID = sanitized uppercase label + 8-hex volume serial
  (e.g. RSDOS-5BD1E55F): unique per format, stable across reboots,
  human-recognizable, machine-parseable (^[A-Z0-9_]+-[0-9A-F]{8}$);
  cloned volumes get a -N suffix.  Public ops take a vol index and
  select it (select_vol also picks the backing AHCI disk), matching
  the ahci::select pattern
- fs.rs: /disk is now a plain directory whose children are one Disk
  node per mounted volume, named by UID; DiskInfo carries vol
- LFN fix: entries are stored last-first on disk — both the writer
  (head-entry first) and reader (append in disk order) were reversed
  and cancelled out for ≤13-char names; multi-entry names (>13 chars)
  read back mangled (e.g. 'from-kernel.txt' as 'xt').  Writer now
  places seq=1 closest to the SFN and seq=N|0x40 first; reader places
  chunks by sequence number and trims at the first NUL.  Verified with
  a 25-char filename round trip: kernel ls/cat correct, mtools shows
  the full LFN, fsck clean on both volumes
- test-disk.sh: test file renamed to disk-test-.txt (>13 chars,
  exercises multi-entry LFN); UID discovered from the boot log; QEMU
  stdio redirected to a log file + EXIT trap so an orphaned QEMU can
  never hang a piped caller (it previously did, 400s)

1 files changed, 2 insertions, 6 deletions

diff --git a/rsdos/src/main.rs b/rsdos/src/main.rs
index 181d3e2..e6b7d2a 100644
--- a/rsdos/src/main.rs
+++ b/rsdos/src/main.rs
@@ -166,15 +166,11 @@ pub extern "efiapi" fn efi_main(image_handle: Handle, system_table: *mut SystemT
     let devices = rsnix::pci::probe();
     rsnix::serial_println!("pci: {} device(s) on all buses", devices.len());
 
-    // Disk: AHCI SATA driver, then mount a FAT32 volume if one is attached.
+    // Disk: AHCI SATA driver, then mount every FAT32 volume under /disk/<UID>/.
     if !rsnix::ahci::init() {
         rsnix::serial_println!("ahci: no disk attached");
     }
-    if rsnix::fat::init() {
-        rsnix::serial_println!("fat: volume mounted at /disk");
-    } else {
-        rsnix::serial_println!("fat: no FAT32 volume");
-    }
+    rsnix::fat::init(); // prints one line per mounted volume
 
     let (dirs, files) = rsnix::fs::init();
     rsnix::serial_println!("fs: vfs ready — {} dirs, {} files", dirs, files);