Skill groups — court-to-group mapping + rounds layout

[javaisbetterthanpython]

Summary

Upstream: pickleball-shuffler#25 (part 2 of 3)

Physical court labels assigned to groups, and rounds page layout that visually groups courts by skill group.

Court-to-group mapping

• Configure at game setup and in-game (Courts/Groups modal).
• Example: Courts 1 & 3 → Standard; Court 2 → Advanced.
• Number of courts per group = number of courts assigned to that group.
• Host can reassign mid-session (triggers pre-gen restart per Richer session mix + instant next round #30).

Rounds page layout

• Same overall rounds page pattern as today — not tabs/pager for groups.
• Courts visually grouped by skill group (clear which courts belong to which group).
• Group courts together in layout as much as possible.

Combined rounds

• When host runs a combined round (Skill groups — separate/combined round generation #35), group court labels disappear for that round (single merged pool display).

Acceptance criteria

• Court labels + assignment to groups on /new and in-game
• Court count per group derived from assignments
• Rounds page shows courts visually grouped by group (separate mode)
• Combined round display hides group labels
• Reassignment invalidates pre-gen (Richer session mix + instant next round #30)
• yarn test:ci and yarn build pass

Files likely touched

• src/CourtsModal.tsx (or new Groups/Courts modal)
• pages/new.tsx
• pages/rounds.tsx
• src/Court.tsx

Dependencies

• Skill groups — foundation (data model + UI) #33 (blocked — groups foundation must exist first)

Upstream reference

• Run multiple groups at once panathea/pickleball-shuffler#25