Align pricing terminology: pixels_per_unit -> pricing_unit_size (track go-livepeer #3942)

Summary

Align the SDK's user-facing pricing terminology with go-livepeer, which is renaming the -pixelsPerUnit flag to -pricingUnitSize (see livepeer/go-livepeer#3942).

Background

pixelsPerUnit is really just a pricing scale factor: it is the number of work units that one quoted price covers, so price_per_work_unit = pricePerUnit / pixelsPerUnit. The "pixels" name is transcoding-era legacy and is confusing for non-video / BYOC / general-runner workloads, where there are no pixels.

go-livepeer#3942 introduces -pricingUnitSize as the primary flag and keeps -pixelsPerUnit as a deprecated alias. The wire/proto field (PriceInfo.pixelsPerUnit) is intentionally left unchanged for compatibility.

What to change in this SDK

User-facing terminology only — the generated proto field stays pixelsPerUnit:

• examples/get_orchestrator_info.py
  • JSON dict key pixels_per_unit -> pricing_unit_size (snake_case analog of pricingUnitSize).
  • Text output ... wei per N pixel(s) -> ... wei per N work unit(s).
  • Keep reading the wire field via info.price_info.pixelsPerUnit.

Out of scope

• src/livepeer_gateway/lp_rpc_pb2.py is generated from the proto and carries the wire field pixelsPerUnit; do not hand-edit it.

Related

• go-livepeer#3942 (flag rename)
• In-flight PR #20 (ja/live-runner) introduced a related unit_scale concept; it should adopt the same pricing_unit_size name for consistency.

Start with examples/get_orchestrator_info.py and inspect how info.price_info.pixelsPerUnit is read. Rename the user-facing JSON key and pixel wording to pricing_unit_size and work units, while leaving src/livepeer_gateway/lp_rpc_pb2.py unchanged; done means the example uses the new terminology without changing the wire field.