Fixes multiple bugs in the Behave step definitions for RelevanceScoringStrategy:
- Use context.strategy_fragments and context.strategy_budget (not context.fragments/context.budget)
- Store assemble result in context.strategy_result (not context.result_fragments)
- Store can_handle result in context.confidence (not context.strategy_confidence)
- Fix step pattern for can_handle with query to use quoted string "{query}"
- Fix step pattern for explain to use quoted string "{text}"
- Fix register_strategy call to pass name and strategy (not just strategy)
- Add RelevanceScoringStrategy to top-level imports
- Add proper type annotations to all new step functions