ExUnit case template for demos.

use PhxDemo.Case
use PhxDemo.Case, viewport: %{width: 1920, height: 1080}, output_dir: "priv/demos"

It wraps PhoenixTest.Playwright.Case, so every PhoenixTest and PhoenixTest.Playwright function is available. :viewport, :output_dir, :check_env, :camera_fixtures (paths checked in pre-flight) and the presentation settings in PhxDemo.settings/1 (:intro, :outro, :captions, :zoom, :trim, …) are handled here; any other option is passed through. The defaults are async: false and ecto_sandbox_stop_owner_delay: 200.

What gets recorded

1. A one-frame-ish magenta "sync" flash on the blank page. The timeline clock starts at that moment and rendering finds it in the video, so timeline offsets are frame-accurate. It's trimmed away.
2. The intro card (if enabled).
3. The demo body.
4. A final screenshot for drift checks (PhxDemo.Drift), then the outro card.

Before the first demo runs, PhxDemo.Env.check_once!/0 verifies the endpoint is serving and assets are built. Disable that with check_env: false. The same pre-flight verifies that every fixture file named literally in an upload/4, drop_files/4, upload_audio/4 or use_microphone/3 call exists (see PhxDemo.Fixtures).

Define demos with demo/3 instead of test/3. A plain test in the same module runs without recording.