feat(proxmox): v1 VM delete + task-status endpoints with protected-VMID guard

[pparage]

Summary

• Adds DELETE /v1/proxmox/hosts/{host_id}/vms/{vmid} — destroys the guest on Proxmox (purge=1 + destroy-unreferenced-disks=1 when purge), with the protected-VMID guard enforced unconditionally on the delete path (VMID 100/101 + canonical ranges + per-host overrides can never be destroyed). Running guest → 409; auth/unreachable/other → existing error envelope.
• Adds GET /v1/proxmox/hosts/{host_id}/tasks/{upid:path}/status — polls a launched action's UPID to real completion. UPID declared as {upid:path} (colons preserved) and percent-encoded (quote(..., safe='')) for the outbound Proxmox call. New TaskStatus schema; unexpected status values coerced defensively so they can't escape the error envelope as a 500.
• Refactors the inline VMID guard into a shared _assert_vmid_safe(row, vmid, action) — behavior preserved for vm_status_action (still gated by _DESTRUCTIVE_ACTIONS), called unconditionally by vm_delete.
• Hardens running-guest detection (matches qemu/LXC phrasings + explicit Proxmox 409).
• Fixes a latent NameError: Any on the retired v0 delete path (app/routes/vms.py).

These endpoints back the deployer-ui "Proxmox Action Tracking" feature (confirmed delete/lifecycle tracked to task completion via UPID polling).

Test Plan

• pytest — 391 passed
• test_vm_delete_happy_path (purge params), test_vm_delete_refuses_protected_vmid (VMID 100 → 409, no DELETE reaches Proxmox), test_vm_delete_running_guest_conflict, test_vm_delete_running_guest_qemu_process_phrasing
• test_task_status_stopped_ok (percent-encoded UPID in outbound URL), test_task_status_stopped_error, test_task_status_unexpected_status_coerced_to_stopped
• Existing test_vm_action_guards_protected_vmids_on_destructive still passes (guard refactor behavior-preserving)