Multiplayer UX: replace transport-first invites with one people-first Play Together flow #131

Parent: #127

Problem

The current in-game Home flow asks Invite friend → Nearby / Online friend → choose person/group. That exposes transport/context before the user has chosen who they want to play with.

For TrainerOS, Nearby/Online are usually implementation circumstances, not the activity the user is choosing.

Goal

Make the primary action Play together / Invite players, then show relevant people and groups in one picker.

Invite players

NEARBY
  Sveta                 Nearby
  Alex                  Nearby

FRIENDS
  Mike                  Online
  Kate                  Online

GROUPS
  Retro Night           6 members
  Sunday Games          4 members

If the same person is available through more than one route, present one person. TrainerOS chooses/prepares the supported route automatically where possible.

Nearby / Online may remain compact status or troubleshooting detail. Do not force the player to understand LAN, relay, traversal, Bluetooth or runtime transport.

Reverse join

The same vocabulary applies from Social: friend's activity → Join / Ask to join; accepted request → existing party; free-entry group policy → deliberate Join without another organizer prompt.

Transport exceptions

Only ask for a route when there is a genuine user-visible tradeoff that TrainerOS cannot resolve safely. Such a choice should be contextual and explained, not the default first screen.

Acceptance

• In-game Home no longer starts with a transport taxonomy.
• Inviting a known friend is one direct person-first journey.
• Duplicate nearby/online identities do not appear as two unrelated people.
• The same Invite/Join wording is used in Social and Home where semantics match.
• Existing compatibility, nearby/online and no-manual-network-setup guarantees remain intact.