fix(matrix): upload retry/backoff, robust MatrixError, typed m.direct, reliable presence on unload

- uploadContent: bounded retry (max 3) reusing rateLimitedActions' capped
  exponential backoff; retries only transient failures (network/429/5xx), never 4xx.
- Robust MatrixError construction from UploadResponse / unknown error shapes.
- addRoomIdToMDirect/removeRoomIdFromMDirect: drop `as any`, use typed
  EventType.Direct + MDirectContent.
- usePresenceUpdater: keep fetch({keepalive}) for the unload offline-presence
  update (sendBeacon can't set the auth header) and log redacted warnings instead
  of silently swallowing presence errors.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/hooks/usePresenceUpdater.ts

@@ -23,6 +23,13 @@ export function usePresenceUpdater() {
     const readStatus = () =>
       userId ? (localStorage.getItem(`lotus-status-msg-${userId}`) ?? '') : '';
 
+    // Log presence failures without leaking PII (user id, token, status message).
+    const warnPresenceFailure = (presence: string, err: unknown) => {
+      const reason =
+        err instanceof Error ? err.message : typeof err === 'string' ? err : 'unknown error';
+      console.warn(`Failed to set presence to "${presence}":`, reason);
+    };
+
     const setOnline = () => {
       const status = readStatus();
       return mx
@@ -30,7 +37,7 @@ export function usePresenceUpdater() {
           presence: 'online',
           ...(status ? { status_msg: status } : {}),
         })
-        .catch(() => undefined);
+        .catch((err) => warnPresenceFailure('online', err));
     };
     const setUnavailable = (statusMsg?: string) => {
       const status = readStatus();
@@ -39,10 +46,12 @@ export function usePresenceUpdater() {
           presence: 'unavailable',
           ...(statusMsg ? { status_msg: statusMsg } : status ? { status_msg: status } : {}),
         })
-        .catch(() => undefined);
+        .catch((err) => warnPresenceFailure('unavailable', err));
     };
     const setOffline = () =>
-      mx.setPresence({ presence: 'offline', status_msg: '' }).catch(() => undefined);
+      mx
+        .setPresence({ presence: 'offline', status_msg: '' })
+        .catch((err) => warnPresenceFailure('offline', err));
 
     // Manual presence overrides — no activity tracking needed.
     if (hidePresence || presenceStatus === 'invisible') {
@@ -100,6 +109,11 @@ export function usePresenceUpdater() {
       const baseUrl = mx.getHomeserverUrl();
       if (!userId || !token || !baseUrl) return;
 
+      // Reliable delivery during page teardown: navigator.sendBeacon cannot set the
+      // Authorization header required by the authenticated Matrix presence endpoint, so
+      // it isn't usable here. fetch(..., { keepalive: true }) lets the request outlive the
+      // page and is the correct mechanism for an authed endpoint. (keepalive bodies are
+      // capped at 64KB, which this tiny payload is well under.)
       fetch(`${baseUrl}/_matrix/client/v3/presence/${encodeURIComponent(userId)}/status`, {
         method: 'PUT',
         headers: {
@@ -108,7 +122,7 @@ export function usePresenceUpdater() {
         },
         body: JSON.stringify({ presence: 'offline' }),
         keepalive: true,
-      }).catch(() => undefined);
+      }).catch((err) => warnPresenceFailure('offline (pagehide)', err));
     };
 
     setOnline();