Exposes the scenario engine (platform.System.RunScenario, added earlier)
in the web UI instead of only the `bee run` CLI: a new nav item lists every
scenarios/*.json found on mounted removable media (GET /api/scenario/list)
and runs one with a click (POST /api/scenario/run), enqueued as a normal
Task with target "scenario" — progress/logs live in Tasks like any other
SAT pack, no separate live-output UI needed.
- app.go: satRunner gains RunScenario, exportManager gains
ListScenarioFilesOnRemovableMedia/ReadScenarioFromRemovableMedia — both
already implemented on platform.System, just newly exposed through App.
- webui/tasks.go: taskParams.ScenarioName; runTask's "scenario" case reads
the file from removable media, parses it, and runs it.
- webui/page_scenario.go: the page itself.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>