fix: complete the deploy-tool dependency gate (end the whack-a-mole)

deploy-disk.sh had its own hardcoded tool check that was out of sync with
check-host-deps.sh, so builds got past the host gate and then failed at
deploy time with "missing host tool mkfs.btrfs" (btrfs-progs was never in
check-host-deps.sh).

- check-host-deps.sh: add mkfs.btrfs/btrfs (btrfs-progs) plus curl/git so
  `make deps` / check-host-deps --install covers the entire build + deploy
  path in one go.
- deploy-disk.sh: pre-flight now checks the full tool set (sgdisk,
  partprobe, mkfs.btrfs, btrfs, rsync, wipefs, truncate, + mkfs.vfat for
  efi) and reports ALL missing tools at once with the exact apt install
  command, instead of dying on the first one.
- build-live.sh: the live image explicitly installs gdisk, parted,
  dosfstools, btrfs-progs, rsync so the graphical installer always has the
  deploy tooling regardless of edition.

scripts/check-host-deps.sh

@@ -33,6 +33,12 @@ NEEDED=(
   "sbverify|sbsigntool"
   # hybrid ISO: mtools builds the embedded EFI image that grub-mkrescue uses
   "mformat|mtools"
+  # deploy path (deploy-disk.sh): partition, btrfs, and copy tooling
+  "mkfs.btrfs|btrfs-progs"
+  "btrfs|btrfs-progs"
+  # toolchain / vendor downloads
+  "curl|curl"
+  "git|git"
 )
 
 MISSING=()