REOPENED. PDF + Excel exporters read non-existent dict keys, so demand/supply/
scenario columns silently rendered "—". Tests passed only because the fixtures
were stale (hand-typed the same wrong keys → fixture agreed with buggy exporter).
- future_market: demand/supply → projected_demand_units/projected_supply_units
- scenarios: drop non-existent per-scenario "overall"; show primary-horizon
deficit_index from ScenarioForecast.forecasts (scoring.overall was NOT broken)
- Excel #991: add missing future_supply (index + breakdown) + confidence.factors
sections; add future_supply to PDF for parity
- tests: rebuild forecast/scenario fixtures from real DemandSupplyForecast /
ScenarioForecast as_dict(); contract-key regression guards fail on key-drift
(verified: reintroducing old keys fails the new tests). 28 passed.
Refs #989#991
