0.6.7: rejoin, call membership, rotation, no telemetry

Production-signed 0.6.7 (30). Android 13 or later. Update over 0.6.6; do not uninstall first.

• Rejoining a room works first time. A tap made while the last room is still closing waits and is carried out, instead of being dropped silently.
• Media starts as soon as the room's secure epoch is ready, instead of on a single retry 30 seconds later.
• Call membership: the phone now tells the room when it is on a call and reads when others are, so desktop and web show Join call against a phone that is on one, and the phone shows it for theirs.
• The app turns with the phone all four ways, honouring the system rotation lock.
• Google's usage reporting is removed from background effects (MediaPipe) and the QR scanner (ML Kit). A build check fails if the reporting library returns.
• New join-path logging (tag KithMootJoin) for diagnosing slow connections.

APK SHA-256: a1f4c64b1c296d4eb66bbfdbbfc18206b0d5cc7815e1e92592d64597f4521a5a
Certificate SHA-256: 135bcabf715216d13b7a596c6f891c3220a7f90826ef8e75930d51b34506a2e9