fix(presence): Do Not Disturb is real "busy" presence and keeps your status (#283)

DND was sent as presence unavailable with the literal status text
"dnd": it replaced your status, and other clients showed "dnd". Where
the server supports MSC3026 (busy_presence), DND now sends presence
org.matrix.msc3026.busy and leaves the status alone (Synapse keeps
busy across /sync set_presence=online). Busy renders as red "Do Not
Disturb" with the real status line; the legacy unavailable + "dnd"
encoding is still recognised and still used on servers without it.
Status saves / clears no longer downgrade busy. The SDK rejects
non-spec presences, so busy goes through a direct authed PUT.

Fixes #283

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/components/presence/Presence.tsx

@@ -13,11 +13,13 @@ import {
 import React, { ReactNode } from 'react';
 import * as css from './styles.css';
 import { Presence, usePresenceLabel } from '../../hooks/useUserPresence';
+import { isDndPresence } from '../../utils/busyPresence';
 
 const PresenceToColor: Record<Presence, MainColor> = {
   [Presence.Online]: 'Success',
   [Presence.Unavailable]: 'Warning',
   [Presence.Offline]: 'Secondary',
+  [Presence.Busy]: 'Critical',
 };
 
 type PresenceBadgeProps = {
@@ -31,9 +33,11 @@ export function PresenceBadge({ presence, status, size }: PresenceBadgeProps) {
   // Disturb" to match PresenceRingAvatar and the settings picker (which both
   // special-case 'dnd' → Critical) — the badge was the lone outlier showing a
   // yellow "Idle". The 'dnd' sentinel isn't surfaced as a status line.
-  const isDnd = presence === Presence.Unavailable && status === 'dnd';
+  // [Gitea #283] or MSC3026 busy, which keeps a real status line.
+  const isDnd = isDndPresence(presence, status);
+  const legacyDnd = isDnd && status === 'dnd';
   const displayLabel = isDnd ? 'Do Not Disturb' : label[presence];
-  const displayStatus = isDnd ? undefined : status;
+  const displayStatus = legacyDnd ? undefined : status;
   const ariaLabel = displayStatus ? `${displayLabel} — ${displayStatus}` : displayLabel;
 
   return (