New scenario types beyond baseline / competitive / crisis

## Context
Only three scenario archetypes exist today. Launches face other shocks.

## Proposed work
- Add scenario types such as price change, feature launch, influencer endorsement, PR event, and regulatory shock, each with its own event injection.

## Acceptance criteria
- [ ] At least 3 new selectable scenario types
- [ ] Each injects an appropriate event and is comparable in the dashboard