- The strategy/preset lists were loaded once with failures swallowed, so a
single failed first request left the strategy dropdown empty forever. They
are now retried every 3s until populated.
- Clearer collapse affordance: hover highlight, a hide/show hint, and a
tooltip; Backtest and Parameter sweep start collapsed so the strategy
selector and status are immediately visible.
- Adds an integration test that the strategy dropdown is populated and the
panel actually collapses.
