feat: add 'vol' command

programs/include/montauk/syscall.h

@@ -514,6 +514,10 @@ namespace montauk {
     inline int partlist(montauk::abi::PartInfo* buf, int max) {
         return (int)syscall2(montauk::abi::SYS_PARTLIST, (uint64_t)buf, (uint64_t)max);
     }
+    // One entry per mounted volume (one filesystem, i.e. one drive number).
+    inline int volinfo(montauk::abi::VolInfo* buf, int max) {
+        return (int)syscall2(montauk::abi::SYS_VOLINFO, (uint64_t)buf, (uint64_t)max);
+    }
 
     // Raw block device I/O (driver-agnostic)
     inline int64_t disk_read(int blockDev, uint64_t lba, uint32_t sectorCount, void* buf) {