Rewrite the three structurally-identical m2m-join readers
(portfolio_functions.aggregate_portfolio_recommendations,
Outputs.get_recommendations_from_db, export get_recommendations) to join
PlanModel directly via recommendation.plan_id, dropping the plan_recommendations
join and its now-unused import. The writers set plan_id (prior slice), so the
rows resolve. test_export pins the export reader through the cut (its fixtures
now set recommendation.plan_id). A portfolio_functions DB characterization test
lands with the scenario consolidation (which provides the full-parity scenario
table the aggregation writes to).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
