Android: message notification vibration is much longer and stronger than a standard notification

**Observed** (Buzz Android app, Samsung Galaxy Z Fold8 / One UI, 2026-09-04): every incoming-message notification vibrates noticeably longer and stronger than notifications from other apps on the same phone. The user described it as "too long and too strong, feels abnormal" compared to a normal notification buzz.

**Expected**: the message notification channel uses the system default vibration (short, same as other apps), or the pattern is configurable in the app's notification settings.

**Impact**: a user who receives messages from several active channels gets a long buzz per message; with busy channels this becomes disruptive enough that the user considers muting the app entirely.

**Possible workaround**: overriding the vibration pattern for the Buzz notification category in Android system settings (One UI allows per-category patterns).

**Notes**: reported by the app user; we have not traced the source yet. If a custom `vibrationPattern` is set on the Android notification channel, using the system default would likely address this. Happy to provide the app version and device logs on request.