feat: add get_lineups() and get_formations()

[johnhegs]

Summary

Adds get_lineups(uid) and get_formations(), covering Spond's match line-ups — the arrangement of players for a fixture, set in the mobile app.

get_lineups(uid) returns one dict per line-up, as an event may hold more than one. Every player entry carries normalised pitch coordinates x and y in the range 0.0–1.0, with y measured from the opponent's goal to the team's own, so the arrangement can be reconstructed rather than just listed. Where a player is assigned to the slot, the entry also carries a membershipId (joining to get_groups()) and a playerName; a formation slot with nobody assigned omits membershipId and has an empty or absent playerName. formationId is absent when players were positioned freely rather than from a template.

get_formations() returns the formation catalogue (52 entries, team sizes 5–11) used to resolve formationId to a name such as 4-4-2. It is static and shared across all groups, so it is cached on self.formations in line with the other lookups.

Line-ups carry visibility: "HOSTS_AND_ADMINS_ONLY", indicating they are readable only by an event's hosts and admins.

Both are read-only GETs against the existing core/v1 base URL and need only the usual Bearer token. examples/lineups.py prints a text pitch diagram per line-up.

Notes

• positions[].name in the formation catalogue is a localisation key such as lineup_football_goalkeeper, not a display string. Documented in the docstring.
• Neither new method checks r.ok, following get_profile, get_groups and get_event_attendance_xlsx. The file is split on this — get_events and get_posts do check. Happy to add the check if you'd prefer.
• Neither endpoint is documented by Spond, so the same no-guarantees caveat as the rest of the library applies.