fix: health monitor detects down monitors via ip link flags + disables wlan2mon

operstate reports 'unknown' on monitors (normal), so _iface_up now parses
admin flags from ip link. Discovered a second pineapd SIGSEGV source: the
wlan2mon 6GHz monitor this hardware never creates, hopping on the missing
iface (~85s crash cadence even with the SSID pool off). The monitor now
disables it in the fix path.

payload/user/remote_access/pager-webui/server.py

@@ -3341,9 +3341,20 @@ def _sigsegv_count():
     return out.count('SIGSEGV')
 
 
+def _iface_up(name):
+    """True when the interface's admin flags contain UP. Monitor interfaces
+    report operstate 'unknown' even when usable, so parse `ip link` flags."""
+    rc, out, err = device_run(['ip', 'link', 'show', name], timeout=10)
+    if rc != 0:
+        return False
+    m = re.search(r'<([^>]+)>', out or '')
+    if not m:
+        return False
+    return 'UP' in m.group(1).split(',')
+
+
 def _monitor_down(name):
-    rc, out, err = device_run(['iw', 'dev'], timeout=10)
-    return name not in out
+    return not _iface_up(name)
 
 
 def health_check():
@@ -3366,11 +3377,23 @@ def health_check():
         device_run(['uci', 'set', 'pineapd.@ssidpool[0].disable=1'])
         device_run(['uci', 'commit', 'pineapd'])
         h['last_action'] = 'SSID pool broadcast disabled (pineapd crash-loop fix)'
-    elif _monitor_down('wlan1mon'):
-        device_run(['ip', 'link', 'set', 'wlan1mon', 'up'], timeout=10)
-        h['last_action'] = 'wlan1mon brought up'
+    elif _monitor_down('wlan1mon') or _monitor_down('wlan0mon'):
+        for name in ('wlan1mon', 'wlan0mon'):
+            if _monitor_down(name):
+                device_run(['ip', 'link', 'set', name, 'up'], timeout=10)
+        h['last_action'] = 'monitor interfaces brought up'
     else:
-        h['last_action'] = 'pineapd restart'
+        # wlan2mon is a 6GHz monitor this hardware never materializes; with
+        # hop enabled pineapd crashes on the missing iface (second SIGSEGV
+        # source after the SSID pool). Keep it disabled.
+        wlan2 = _uci_section('pineapd.wlan2mon')
+        if wlan2.get('disable') != '1':
+            device_run(['uci', 'set', 'pineapd.wlan2mon.disable=1'])
+            device_run(['uci', 'set', 'pineapd.wlan2mon.hop=0'])
+            device_run(['uci', 'commit', 'pineapd'])
+            h['last_action'] = 'wlan2mon disabled (missing 6GHz iface crash source)'
+        else:
+            h['last_action'] = 'pineapd restart'
     device_run(['/etc/init.d/pineapd', 'restart'], timeout=30)
     h['sigsegv_last'] = _sigsegv_count()
     h['last_fix'] = now