- After a call ends, send a plaintext <call-history/> service message
to the user's own bare JID with direction, status, duration, start
time, peer and video flag plus the call id as origin-id.
- Intercept the payload on live, carbon and MAM paths and upsert the
same system call card on every device; deduplication reuses the
origin-id as clientID, and missed incoming calls bump unread.
- Cover payload parsing and round-trip in CallHistorySyncTests, guard
the namespace and interception in verify.sh, and document the flow
in ARCHITECTURE.md.
