tests: add live VyOS e2e harness on Proxmox

Adds an opt-in end-to-end harness that runs pyvyos against a real
VyOS HTTPS API on a Proxmox VE host.

  tests/pve/      shell-based VM lifecycle on a remote PVE host:
                  preflight, ensure-template (state-machine over the
                  VMID with manual-install phase 1 and cloud-init
                  phase 2), create/start/stop/destroy, run-e2e.
                  Cloud-init seed ISO is generated on the PVE host
                  itself; nothing local-side beyond ssh is required.
                  .env is gitignored; .env.example documents the
                  full set of variables.

  tests/e2e/      pytest suite that exercises the public methods
                  most likely to regress on a payload change:
                  show, retrieve_show_config, configure_set /
                  retrieve_return_values / configure_delete round
                  trip, and configure_multiple_op batch. Auto-skipped
                  unless PYVYOS_E2E=1.

The cloud-init template now sets 'service https api rest' before
the API key. Without that flag VyOS only exposes /info; the other
HTTPS routes return 404. README and tests/pve/README document the
requirement, both for cloud-init and for the manual-fallback path.

Also fixes a pre-existing footgun in pyproject.toml: the pytest-env
defaults overwrote VYDEVICE_HOSTNAME from the shell, which made
the e2e tests silently aim at the stale 192.168.56.100 fixture
host. The entries now use the 'D:' (default) prefix so live runs
can override from the environment as expected.

Validated against VyOS rolling 2026.05.18-0045: 4 e2e + 57 unit
tests pass.

This commit does not change pyvyos HTTP payloads, request handling,
or response parsing.

0 files changed, 0 insertions, 0 deletions