OVRTX render products and AOVs

Start from the public implementation in addon/. Do not add a second bridge or infer a product from an image file.

Baseline contract

• sensor_paths declare render products at simulation creation.
• selected_sensor_paths select products for a request/session.
• RenderVar reads use exact paths such as <product>/LdrColor.
• The native client exposes typed builders such as build_ReadWorldState_ldr_color and, when supported, build_ReadWorldState_hdr_color, plus matching decode helpers.
• Iterator pages, terminal status, completed-sample identity, dimensions, and per-product identity are part of the acceptance contract.

Run the focused public tests before customization: