Task: Implement report pre-processing

Produce the ORE engine's input from a definition's scope: bulk scope reads on trading and market data, mapping to the engine's documents through ore's mappers in-process, streaming, and an archive addressed by a digest of its inputs so that concurrent runs over the same scope share one generation.

• Trading and market data each expose a scope-limited bulk read, and pre-processing reads nothing else.
• The artifact is addressed by a digest of its inputs and a repeated request over the same inputs is a lookup.
• Peak memory is bounded and does not grow with the size of the input.
• The archive contains Input/ore.xml and the files it names, so the grid can run it.

(Implementation strategy. Written when work starts; key decisions are distilled into the parent story's * Decisions at close, but the plan itself stays — it is the historical record of what we did.)

Every number this task claims about a tree, with the command that produced it and the commit it was measured at. A number without both is not a measurement, because a clean-up record describes a tree and trunk moves under a branch: a consumer count, a gate's component count and a suite's size all change with no code changing, and the reader of a bare number cannot tell which tree it came from. Where the raw output matters, put it in an evidence/ file beside the task and name that file in the Command column.

Manual QA scenarios (scaffolded via compass add test_scenario) that verify this task. Link new ones here as they're created; the scenario doc itself links back via its "Verifies task" field.