v0.4.2 — live microVM disk resize

This patch fixes live disk resize for microVMs whose virtio devices have
anonymous QEMU device IDs. Linux stays at 6.12.113, with AppArmor selected
by default.

Disk resize

Proxmox could grow the backing volume and then fail with:

no block node inserted for drive 'scsi0'

The block-info lookup now resolves missing or anonymous virtio device IDs
through the stable legacy backend ID, such as drive-scsi0, for exact microvm
guests. Conventional VMs keep the upstream mapping and top-throttle-node resize
behaviour. The installer handles Blockdev.pm file replacement and requires
independently verified backups for rollback.

The regression suite passes 96/96. An isolated QEMU microVM test uses the
patched Proxmox resize routine to grow the root disk. The separate read-only
cloud-init disk stays unchanged. Tests also cover stopped-VM behaviour, size
rounding, repeat installation, upgrades and rollback refusal. The published
package also passed a live Proxmox resize from 2 to 3 GiB, online filesystem
growth and sequential installation on five hosts without guest restarts. See
published-package validation.

See issue #24 and the
cause and validation notes.

Existing partial resizes

The patch does not repair earlier partial resizes. Check the backing volume,
QEMU node and stored configuration sizes before retrying. An additive retry
can grow storage again; use a verified absolute target. Guest partition and
filesystem growth remain separate steps.

Installation

Install pve-microvm_0.4.2-1_all.deb on each Proxmox host. Installation reloads
pvedaemon to refresh its Perl code. Guest restarts are not required for this
host-side fix. Custom kernel paths and existing guest network files are
preserved.