Extract reusable Roku runtime assertion helpers

[altaywtf]

Goal

Move the reusable, platform-level pieces from the current putio-roku live harness into rokit without baking put.io app journeys into the generic tool.

Candidate generic pieces

• ECP launch and deeplink parameter helpers
• Remote key sequencing and typed key validation
• Active-app and raw query helpers
• SceneGraph node lookup helpers
• Visible, hidden, absent, text, focus, translation, and size assertions
• Developer screenshot capture and deterministic artifact paths
• Small review-artifact primitives that app repos can compose

Boundaries

Keep these in app repos or scenario files:

• put.io content IDs
• account credentials or tokens
• specific playback journeys
• player UI expectations tied to product behavior
• visual reference assets

Proof

The first migration should keep putio-roku green with its existing live harness commands, then switch one app-level scenario to call rokit primitives.