Pixel Party

Fixes portrait invites that looked successful but left every member painting alone on their own copy:

• Invite join-acks now match case-insensitively. Inviting someone as bob works the same as Bob; previously the wrong-cased ack was silently discarded and the invitee never actually joined the roster.
• Typed names adopt the roster's casing everywhere. Re-invites of previously uninvited members lift their tombstone correctly, and uninvites no longer claim a real member "is not a member" over a case typo.
• Re-inviting is now a repair tool. If a portrait stopped syncing for someone under an older version, the creator can simply invite them again — their client re-acks automatically (no popup) and the roster heals.
• Pending invites survive /reload. They persist in SavedVariables with a wall-clock expiry, so reloading between sending an invite and its accept no longer orphans the joiner.