* Show manager username instead of team name on draft board
Both the read-only draft board and the active draft room now display
the manager's username (falling back to displayName if no username is
set, and to team name if the team is unassigned) in the column headers
of the draft grid.
https://claude.ai/code/session_01C97GauJaAB83NVWxdpNVh1
* Address code review: extract ownerMap helper, fix TeamsDraftedGrid
- Extract ownerMap building into app/lib/owner-map.ts to eliminate
duplication across the two loaders
- Guard against null username AND displayName so the map only contains
real string values
- Apply username display to TeamsDraftedGrid (the "Teams" tab in the
active draft room), which was missed in the initial change
https://claude.ai/code/session_01C97GauJaAB83NVWxdpNVh1
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Co-authored-by: Claude <noreply@anthropic.com>
