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.

1 files changed, 29 insertions, 5 deletions

diff --git a/README.md b/README.md
index 83dbd90..1f9ce19 100644
--- a/README.md
+++ b/README.md
@@ -24,10 +24,15 @@ Requires **Python 3.11 or newer**. Tested on 3.11, 3.12, and 3.13.
 Enable the HTTPS API on the VyOS device and create an API key:
 
 ```text
+set service https api rest
 set service https api keys id my-key key 'your-secret-key'
 commit
 ```
 
+> The `set service https api rest` line is required. Without it the
+> HTTPS service only exposes `/info` and every other endpoint returns
+> `404`. See the VyOS docs for the [HTTP API service](https://docs.vyos.io/en/latest/configuration/service/https.html).
+
 Then, from Python:
 
 ```python
@@ -206,13 +211,22 @@ handed back to the caller.
 
 ## VyOS compatibility
 
-Tested against:
+Tested live against:
+
+- VyOS rolling `2026.05.18-0045` (current rolling at release time)
 
-- VyOS 1.4 LTS (stable)
-- VyOS 1.5 rolling
+The library only depends on the HTTPS API surface, so older 1.4 / 1.5
+builds that expose the same endpoints should work without changes,
+but they are not exercised on every release. The live harness under
+[`tests/pve/`](tests/pve/) makes it easy to re-run the suite against
+any VyOS build you care about.
 
-The library only depends on the HTTPS API surface, so versions that expose
-the same endpoints should work without changes.
+Required device-side configuration for the live API:
+
+```text
+set service https api rest
+set service https api keys id <id> key '<secret>'
+```
 
 ## Development
 
@@ -231,6 +245,16 @@ pip install pre-commit
 pre-commit install
 ```
 
+### Live VyOS testing
+
+The regular test suite is mock-based and does not need a VyOS device.
+
+For maintainers, this repository ships an opt-in harness under
+[`tests/pve/`](tests/pve/) that creates a disposable VyOS VM on a
+local Proxmox host and runs `tests/e2e` against the real HTTPS API.
+It is not part of the default GitHub Actions workflow. See the
+harness README for setup.
+
 ## Contributing
 
 Bug reports and pull requests are welcome. Please open an issue first to