Alerts desk: add filtering/grouping – a severity filter, a ‘collapse repeats’ toggle, and a way to mute HUB demand churn – the 24h history is dominated by deman

WHAT: The Alerts 24h history is mostly HUB churn (dozens of ‘Dehumidifier/Heater demand on/off’), repeated zigbee CLEAR-banner NOTEs, and restart-triggered advisories – the signal (real ALERTs like the clone dark-period violation) is buried. Logs has a ‘Hide system rows’ toggle but the Alerts desk has no filtering. WHY: an operator scanning for what matters has to wade through switching noise. NEXT: add a severity filter (ALERT/HUB/NOTE), a ‘collapse repeats across restarts’ option, and a default that de-emphasises routine demand toggles. Complements the two Alerts bug rows (advisory-as-ALERT, zigbee jargon). Found live 8.2.0.