Direct "invite this teammate" to a live session — one-tap join, no code

[kipavy]

Part of the team-ux initiative (brainstorm 2026-07-24).

Blocked by: #67 (needs the receive-side notification channel).

Problem

Even with a shorter code (#65), the flow is unchanged: host generates something, ferries it out-of-band, guest brings it back in. For people who are already your teammates that's needless — Voltius already knows the team roster and their online state (member.is_online, src/services/connectionPresence.ts). The "zero-friction / magic" version is: pick the person, they get a knock, one tap = in.

Proposed reflow

• In ShareMenu.tsx, add an "Invite people" section listing team members with online dots (reuse presence).
• Tap a member → server pushes a direct session invite to them → they get a notification (via Unified team notification inbox — invites, shared sessions & control requests through the bell + toasts #67) → one tap = joined (drops them into the multiplayer tab, same as a Team Sessions card join today).
• Code/link (Multiplayer session share: human-friendly code + auto-copy + QR (drop the raw id:token string) #65) remains the fallback for outsiders / non-teammates.

Decisions (brainstorm 2026-07-24)

• Scope to teammates in a shared team/vault context (we already have identity + a key relationship with them). Outsiders stay on the code path.
• Offline teammates: invite still deliverable — surfaces in their inbox (Unified team notification inbox — invites, shared sessions & control requests through the bell + toasts #67) next time online, with the session's live/ended state reflected.

Still open

• Server push channel for a direct per-user session invite (reuse pending-invitation infra in teamService.ts, or the presence/ws transport?).
• Whether to show all teammates or only those with access to the underlying connection/vault.
• De-dupe against the existing vault-broadcast path (a member who'd already see the session in their Team Sessions rail shouldn't get a redundant knock).