Mobile: channel members list shows no online/presence indicator for members (desktop sidebar does)

[Tony-ooo]

Summary

On mobile, the channel Members sheet (People / Agents) shows only an avatar, a display name, and a static role label ("Owner" / "Member" / "Agent"). There is no online/away/offline indicator, so it is impossible to tell at a glance whether a member — especially an agent — is reachable before @mentioning them. In agent-heavy channels, nearly every row is a bot with no liveness signal unless it happens to be mid-generation ("Working…").

Desktop already overlays a presence dot on every member card in the channel sidebar, so this is a client parity gap rather than a missing platform capability.

Source verification (main @ 040b203f)

The mobile members sheet renders each tile with this subtitle priority — none of the branches is presence:

1. "Working…" spinner — only while a bot is actively generating (workingBotPubkeysProvider)
2. NIP-38-style custom status text — people only; bots are deliberately excluded from userStatusCacheProvider.track() (mobile/lib/features/channels/members_sheet.dart:73-80)
3. Static role label otherwise (members_sheet.dart:232-265)

_MemberAvatar is a plain AvatarImage with no badge/dot (members_sheet.dart:439-453). Tapping through to a profile does show presence (the "Presence: Online/Away/Offline" chip in mobile/lib/features/profile/user_profile_sheet.dart), which makes the list view feel inconsistent.

Everything needed already exists elsewhere in the mobile app:

• Live kind:20001 subscription + per-pubkey cache: PresenceCacheNotifier (mobile/lib/features/profile/presence_cache_provider.dart), with track(pubkeys) to filter updates
• Reusable avatar presence-dot geometry: AvatarBadgeMaskGeometry.presenceDot (mobile/lib/shared/widgets/masked_avatar_badge.dart), documented as "Desktop's sidebar presence treatment"
• A working in-app precedent: the DM header tracks the peer and renders MaskedAvatarBadge(geometry: AvatarBadgeMaskGeometry.presenceDot) from presenceCacheProvider (mobile/lib/features/channels/channel_detail_page/app_bar.dart:218-251)

Desktop parity reference: desktop/src/features/channels/ui/MembersSidebarMemberCard.tsx:172-179 overlays PresenceDot on each avatar when presenceStatus is available (data-testid="sidebar-member-presence-*").

Suggested enhancement

In MembersSheet:

1. Track presence for all listed members (people and agents) via presenceCacheProvider.track(...)
2. Render an online/away/offline dot per tile — e.g. a MaskedAvatarBadge presence-dot overlay on each _MemberAvatar, matching the DM header treatment and desktop's sidebar

This gives users an at-a-glance answer to "who can I actually reach right now?" before typing a mention.

Related but distinct

• Mobile: agent presence shows offline after relay reconnect — no snapshot backstop, unlike desktop #6200 covers a separate data-accuracy bug (mobile presence cache misses current state after reconnect, since it is subscribe-only with no snapshot backstop). Fixing that would make this new indicator more reliable, but adding the indicator is independent.