Enhance fault alert system with region-based scoping and banned channels

Updated the fault alert functionality to include an optional region name for scoping alert floods, allowing operators to override the default scope. Introduced a list of banned channels (e.g., Public PSK, `#test`, `#bot`) to prevent spamming community channels with alerts. The implementation ensures that alerts are only sent to private PSKs or non-banned hashtags. Relevant changes were made across multiple files, including updates to the CLI for setting and retrieving the new `alert.region` preference.

examples/simple_repeater/MyMesh.cpp

@@ -956,6 +956,7 @@ MyMesh::MyMesh(mesh::MainBoard &board, mesh::Radio &radio, mesh::MillisecondCloc
   _prefs.alert_enabled = 0;
   _prefs.alert_psk_b64[0] = '\0';
   _prefs.alert_hashtag[0] = '\0';
+  _prefs.alert_region[0] = '\0';      // empty = use default_scope
   _prefs.alert_wifi_minutes = 30;     // 30 minutes
   _prefs.alert_mqtt_minutes = 240;    // 4 hours
   _prefs.alert_min_interval_min = 60; // re-arm window: 1 hour
@@ -1088,7 +1089,10 @@ void MyMesh::begin(FILESYSTEM *fs) {
 #endif
 
   // Wire fault-alert reporter. begin() is safe regardless of bridge state.
-  _alerter.begin(&_prefs, this);
+  // Passing `this` as the callbacks lets the reporter resolve a TransportKey
+  // scope (alert.region override, falling back to default_scope) so alert
+  // floods ride the same scope as adverts/channel messages.
+  _alerter.begin(&_prefs, this, this);
 #if defined(WITH_MQTT_BRIDGE)
   _alerter.setBridge(bridge);
 #endif
@@ -1119,6 +1123,24 @@ void MyMesh::sendFloodScoped(const TransportKey& scope, mesh::Packet* pkt, uint3
   }
 }
 
+bool MyMesh::resolveAlertScope(TransportKey& dest) {
+  // Prefer an explicit alert.region override; look it up lazily via
+  // RegionMap so the operator can name a region that doesn't exist yet
+  // without polluting region_map state — we just silently fall through
+  // to default_scope on miss.
+  if (_prefs.alert_region[0]) {
+    auto r = region_map.findByNamePrefix(_prefs.alert_region);
+    if (r && region_map.getTransportKeysFor(*r, &dest, 1) > 0 && !dest.isNull()) {
+      return true;
+    }
+  }
+  if (!default_scope.isNull()) {
+    dest = default_scope;
+    return true;
+  }
+  return false;
+}
+
 void MyMesh::applyTempRadioParams(float freq, float bw, uint8_t sf, uint8_t cr, int timeout_mins) {
   set_radio_at = futureMillis(2000); // give CLI reply some time to be sent back, before applying temp radio params
   pending_freq = freq;