tofu(proxmox): use debian generic image + serial console to fix first-boot kernel panic (bpg#1639)

Co-Authored-By: Claude Opus 4.8 <[email protected]>

infra/tofu/variables.tf

@@ -159,20 +159,24 @@ variable "image_source" {
   description = <<-EOT
     Source URL for the base OS cloud image (qcow2), downloaded to image_datastore
     by proxmox_virtual_environment_download_file. Default is Debian 12 (bookworm)
-    genericcloud amd64 — same image as the pre-migration libvirt module.
+    generic amd64 (full firmware/driver, hybrid BIOS/UEFI). Use `generic`, NOT
+    `genericcloud`: the genericcloud image panics with "Attempted to kill init" on
+    import + disk-resize under bpg (bpg issue #1639).
   EOT
   type        = string
-  default     = "https://cloud.debian.org/images/cloud/bookworm/latest/debian-12-genericcloud-amd64.qcow2"
+  default     = "https://cloud.debian.org/images/cloud/bookworm/latest/debian-12-generic-amd64.qcow2"
 }
 
 variable "image_file_name" {
   description = <<-EOT
     File name the cloud image is stored as on image_datastore. With `import`-content
     storage (PVE 8.2+) the native .qcow2 name is used directly — the old .img rename
-    was an `iso`-content workaround and is no longer needed.
+    was an `iso`-content workaround and is no longer needed. Uses the `generic`
+    (full firmware/driver, hybrid BIOS/UEFI) image, NOT `genericcloud`: genericcloud
+    panics with "Attempted to kill init" on import + disk-resize (bpg issue #1639).
   EOT
   type        = string
-  default     = "debian-12-genericcloud-amd64.qcow2"
+  default     = "debian-12-generic-amd64.qcow2"
 }
 
 # --- cloud-init identity ----------------------------------------------------