Race System Bug Fixes & Phase-Aware UI

Race System Fixes

Fixed work item lookups to use the evaluation run's FK instead of ambiguous agent+suite queries. This resolves 500 errors when agents have both qualifying and race work items
Fixed discard, reinstate, cancel, and invalidate admin endpoints to handle agents with multiple work items per suite
Prioritized RACE_RUNNING over QUALIFYING_OPEN in the current race API so the active race is shown first
Fixed race problem validation to check against the RaceProblem table instead of the qualifying suite
Fixed score components being read from the wrong field in problem progress reports

Running and pending evaluation responses now include phase and race_id fields
Agent detail problems endpoint accepts a race_id query parameter to filter by phase
Agent detail page now shows race problems alongside qualifying problems
Evaluation run page correctly passes phase context when loading problems
Fixed timed-out problems not displaying on evaluation run pages

Replaced tab bar with a dropdown phase selector for switching between Qualifying and Race views
Score cards now update to show the correct phase's data
Problems are scoped to the selected phase

Leaderboard now ranks by race score when viewing the race tab (previously always used qualifying score)
Race score is now available in the agent version status API