fix(calls,matrix): address review findings from agent code review

- CallEmbed watchdog now SELF-HEALS: a genuine ready/joined signal arriving
  after the 25s timeout clears the error and notifies subscribers with
  undefined, so a slow-but-successful EC load no longer strands the user on
  the recovery screen over a live call. Listener dispatch wrapped in try/catch.
- ringtones: synth notes route through a per-session master gain; stop() ramps
  it to 0 so the ring is silenced instantly on answer instead of letting the
  last scheduled phrase ring out over call audio.
- IncomingCallBanner: ping fires exactly once per incoming call (guarded by
  refEventId) instead of re-pinging when ringtone settings change mid-banner.
- focusCameraParticipant: try multiple tile selectors (EC labels vary by
  version), defer the tile click past EC's async spotlight layout switch
  (rAF x2), and dev-warn when no tile matches so testers get signal.
- uploadContent: a cancelled upload (mx.cancelUpload -> AbortError) is no
  longer treated as retryable — previously the retry loop could resurrect an
  upload the user just cancelled. Also retry on 408.
- addRoomIdToMDirect/removeRoomIdFromMDirect: guard against a corrupt m.direct
  whose values aren't arrays.

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

src/app/utils/matrix.ts

@@ -169,12 +169,17 @@ const matrixErrorFromUnknown = (e: unknown): MatrixError => {
 // HTTP statuses that should not be retried — client errors are deterministic
 // (e.g. 413 payload too large, 400 bad request, 401/403 auth) and won't succeed on retry.
 const isRetryableUploadError = (e: unknown): boolean => {
+  // A user-cancelled / aborted upload must never be retried. matrix-js-sdk's
+  // mx.cancelUpload() rejects the upload with a DOMException named "AbortError";
+  // without this guard the retry loop would resurrect an upload the user just
+  // cancelled.
+  if ((e as { name?: unknown } | null | undefined)?.name === 'AbortError') return false;
   if (e instanceof MatrixError) {
     const status = e.httpStatus;
     // No status => network/transport failure (transient): retry.
     if (typeof status !== 'number') return true;
-    // Retry on rate-limiting and server-side (5xx) errors only.
-    return status === 429 || status >= 500;
+    // Retry on request-timeout, rate-limiting and server-side (5xx) errors only.
+    return status === 408 || status === 429 || status >= 500;
   }
   // Non-Matrix errors are typically network/transport failures: retry.
   return true;
@@ -307,6 +312,8 @@ export const addRoomIdToMDirect = async (
   // (it can only be a DM room for one person)
   Object.keys(userIdToRoomIds).forEach((targetUserId) => {
     const roomIds = userIdToRoomIds[targetUserId];
+    // Guard against a corrupt m.direct where a value isn't an array.
+    if (!Array.isArray(roomIds)) return;
 
     if (targetUserId !== userId) {
       const indexOfRoomId = roomIds.indexOf(roomId);
@@ -316,7 +323,7 @@ export const addRoomIdToMDirect = async (
     }
   });
 
-  const roomIds = userIdToRoomIds[userId] || [];
+  const roomIds = Array.isArray(userIdToRoomIds[userId]) ? userIdToRoomIds[userId] : [];
   if (roomIds.indexOf(roomId) === -1) {
     roomIds.push(roomId);
   }
@@ -334,6 +341,7 @@ export const removeRoomIdFromMDirect = async (mx: MatrixClient, roomId: string):
 
   Object.keys(userIdToRoomIds).forEach((targetUserId) => {
     const roomIds = userIdToRoomIds[targetUserId];
+    if (!Array.isArray(roomIds)) return;
     const indexOfRoomId = roomIds.indexOf(roomId);
     if (indexOfRoomId > -1) {
       roomIds.splice(indexOfRoomId, 1);