Task: Use the engine's idempotency check in the reporting handlers

Every reporting step converges when the engine re-dispatches it, so a run that a restart recovered does the work of each phase once.

• A re-dispatched assemble_bundle does not write a second bundle row.
• A re-dispatched gather_trades, gather_market_data or prepare_ore_package does not re-export or re-upload what it produced before.
• A test re-dispatches a completed step and asserts that the phase's effect happened once.

(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.