feat: presence avatar border rings (P5-18) + room emoji prefix support (P5-6)

P5-18: PresenceRingAvatar wrapper component applies a 2px box-shadow
ring to user avatars — green (online), yellow (idle/unavailable), red
(DND via status_msg='dnd'), no ring (offline). Applied to: message
timeline sender avatars, members drawer (members + knock requests),
@mention autocomplete, and inbox notification senders.

P5-6: Leading emoji in room names renders at 1.15× in the sidebar via
Unicode emoji regex detection in RoomNavItem. Emoji picker (EmojiBoard
in PopOut) added to all three room-name inputs: Create Room dialog
(converted to controlled input), Room Settings name field (shown only
when canEditName), and the "Rename for me" local rename dialog.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -138,11 +138,16 @@ Emoji reaction buttons styled for terminal mode via `button[data-reaction-key]`
 
 - **Incoming call ring**: DM calls trigger a ring tone with Answer/Decline UI. 30-second auto-dismiss if unanswered. Implemented in `Room.tsx` and `RoomViewHeader.tsx`.
 
+### Room Customization
+
+- **Room emoji prefix**: A leading emoji in a room name (e.g. 🎮 general) renders at 1.15× size in the sidebar for visual impact. Matrix room names already support Unicode — this is purely a rendering enhancement in `RoomNavItem.tsx`. All three room-name inputs (Create Room, Room Settings, "Rename for me…" dialog) now include a 😊 emoji picker button that prepends the selected emoji to the name field.
+
 ### Presence
 
 - **Discord-style presence selector**: Clicking your avatar in the bottom-left sidebar opens a popout with five status options — Online (green), Idle (yellow), Do Not Disturb (red, broadcasts `unavailable` with `status_msg: 'dnd'`), Invisible (grey outline, broadcasts `offline`), and Auto (activity-tracking, the original behaviour). The selected status persists across reloads via the settings atom. A colored badge on the avatar reflects the current status at a glance. `usePresenceUpdater` short-circuits immediately for manual modes; full idle-timer and visibility-change logic only runs in Auto mode. Settings also exposed via `src/app/state/settings.ts` (`presenceStatus` field).
 - **Custom status message**: Set a short status text (up to 64 characters) with an emoji picker, shown below your display name in member lists and presence displays. Accessible via Settings → Account → Profile. Includes an **auto-clear timer** (options: 30 minutes, 1 hour, 4 hours, 1 day, 3 days, 7 days) — after the timer expires, the status is automatically cleared by setting `status_msg: ''` via `mx.setPresence`. A character counter (shown when ≥ 56/64 chars) prevents overflow. Implemented in `src/app/features/settings/account/Profile.tsx`.
 - **Presence badges on members**: Online/busy/away dots shown next to users in the room members drawer and settings members panel (`PresenceBadge` component from `src/app/components/presence/Presence.tsx`).
+- **Presence avatar border ring**: A 2px colored `box-shadow` ring on user avatars throughout the app shows presence at a glance — green (online), yellow (idle), red (DND), no ring (offline). Implemented as `PresenceRingAvatar` wrapper component (`src/app/components/presence/PresenceRingAvatar.tsx`). Applied to: message timeline sender avatars, members drawer, @mention autocomplete, and inbox notification senders.
 - **Document title unread count**: Tab title updates to `(N) Lotus Chat` for mentions, `· Lotus Chat` for unreads, `Lotus Chat` when clear.
 - **Extended profile fields (MSC4133)**: Settings → Account → Profile includes Pronouns (`m.pronouns`) and Timezone (`m.tz`) fields, saved via MSC4133 `PUT /_matrix/client/unstable/uk.tcpip.msc4133/{userId}/{field}`. Both fields are displayed in user profile panels. Implemented via `src/app/hooks/useExtendedProfile.ts`.
 - **User local time in profile**: When a user has `m.tz` set, their profile panel shows a clock icon, their current local time, and the timezone abbreviation (e.g. EST, JST). Updates every 60 seconds. Respects the viewer's `hour24Clock` setting. Implemented via `src/app/hooks/useLocalTime.ts`.