Task: Refuse a portfolio a trade's party does not own

The versioned trading refactor removed the check that a trade is reported only in its own party's portfolios. The message is gone from the generated SQL, so a trade can be reported into any party's portfolio. Put the guarantee back, or record that it is deliberately gone.

• A trade cannot be reported in another party's portfolio.
• The pgTAP suite that proves it is restored.

(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.