Improve VM lifecycle tooling

Make spawned VMs easier to use and restore from the host.

Add shared DNS and runtime helpers, publish <vm-name>.vm records through mapdns, and teach run/customize/interactive/restore to persist the metadata needed for SSH, DNS cleanup, and clean restores.

Seed per-VM /home and /var disks from the rootfs snapshot so package state is present on first boot, add an interactive customization entrypoint plus ssh.sh and human-friendly list output, and let stop/kill/rm operate on multiple VM identifiers.

Tear down stale TAP, dm, and loop state when VMs stop so restore can recreate them safely, and validate the updated scripts with bash -n plus targeted dry-run harnesses for teardown and restore paths.

README.md

@@ -16,6 +16,7 @@ Minimal Firecracker launcher.
 - `rootfs.ext4`: guest root filesystem (base image if present)
 - `rootfs-docker.ext4`: docker-ready guest rootfs (built via `make-rootfs.sh`)
 - `id_ed25519`: SSH key for `root`
+- `mapdns`: local DNS mapping CLI used to publish `<vm-name>.vm` → guest IP records
 
 ## Run
 ```
@@ -38,6 +39,7 @@ Minimal Firecracker launcher.
 ## Storage Layout
 - `rootfs.ext4` is used as the read-only origin for a per-VM device-mapper snapshot mounted as `/`.
 - Each VM gets writable ext4 disks mounted at `/home` and `/var`.
+- `run.sh` seeds those `/home` and `/var` disks from the rootfs snapshot before boot so the guest sees the base image contents there on first boot.
 - The base image must include `/etc/fstab` entries for `/dev/vdb` → `/home` and `/dev/vdc` → `/var`.
 - `/run` and `/tmp` should be tmpfs via `/etc/fstab`.
 
@@ -46,6 +48,16 @@ Minimal Firecracker launcher.
 ssh -i "./id_ed25519" root@<guest_ip>
 ```
 
+Shortcut:
+```
+./ssh.sh <vm-name-or-ip>
+```
+
+## VM DNS
+- Spawned VMs register `<vm-name>.vm` → guest IP through `mapdns set`.
+- VM teardown removes the mapping through `mapdns rm`.
+- `mapdns` writes to `/home/thales/.local/share/mapdns/records.json`.
+
 ## Internet Access
 VMs do not get internet access by default. You must enable forwarding and NAT:
 ```
@@ -102,10 +114,22 @@ invoke `make-rootfs.sh` to build it.
 `make-rootfs.sh` chooses the first available base image:
 - `./rootfs.ext4`
 
+## Interactive Customization
+To create a writable copy and customize it manually over SSH (no automatic
+package/config changes), use:
+
+```
+./interactive.sh ./rootfs-docker.ext4
+```
+
+You can override the output path:
+```
+./interactive.sh ./rootfs-docker.ext4 --out ./my-rootfs.ext4
+```
+
 ## VM Info File
 Each VM writes:
-- `state/vms/<id>/vm.json`: raw `/vm/config` response from Firecracker.
-- `state/vms/<id>/meta.json`: local metadata (id, name, pid, created_at, guest_ip, tap, api_sock, log, rootfs, kernel, snapshot info).
+- `state/vms/<id>/vm.json`: local metadata under `.meta` plus the raw Firecracker config under `.config`.
 
 ## Log Notes
 - `PCI: Fatal: No config space access function found` and `MissingAddressRange` lines are expected with `pci=off` in `run.sh`.