Add userpref for the packet signature policy default (#11144)

Co-authored-by: Austin <vidplace7@gmail.com>

src/mesh/NodeDB.cpp

@@ -957,6 +957,12 @@ void NodeDB::installDefaultConfig(bool preserveKey = false)
 
     config.security.admin_key_count = numAdminKeys;
 
+    // Left at COMPATIBLE when signature checking is compiled out, so we never report a policy
+    // nothing enforces (mirrors the set-config guard in AdminModule).
+#if defined(USERPREFS_CONFIG_SECURITY_PACKET_SIGNATURE_POLICY) && !(MESHTASTIC_EXCLUDE_PKI) && !(MESHTASTIC_EXCLUDE_XEDDSA)
+    config.security.packet_signature_policy = USERPREFS_CONFIG_SECURITY_PACKET_SIGNATURE_POLICY;
+#endif
+
     if (shouldPreserveKey) {
         config.security.private_key.size = 32;
         memcpy(config.security.private_key.bytes, private_key_temp, config.security.private_key.size);

userPrefs.jsonc

@@ -44,6 +44,7 @@
   // "USERPREFS_LORACONFIG_CHANNEL_NUM": "31",
   // "USERPREFS_LORACONFIG_TX_POWER": "0",
   // "USERPREFS_LORACONFIG_MODEM_PRESET": "meshtastic_Config_LoRaConfig_ModemPreset_SHORT_FAST",
+  // "USERPREFS_CONFIG_SECURITY_PACKET_SIGNATURE_POLICY": "meshtastic_Config_SecurityConfig_PacketSignaturePolicy_PACKET_SIGNATURE_POLICY_BALANCED", // Authenticity policy applied to remotely received packets.
   // "USERPREFS_USE_ADMIN_KEY_0": "{ 0xcd, 0xc0, 0xb4, 0x3c, 0x53, 0x24, 0xdf, 0x13, 0xca, 0x5a, 0xa6, 0x0c, 0x0d, 0xec, 0x85, 0x5a, 0x4c, 0xf6, 0x1a, 0x96, 0x04, 0x1a, 0x3e, 0xfc, 0xbb, 0x8e, 0x33, 0x71, 0xe5, 0xfc, 0xff, 0x3c }",
   // "USERPREFS_USE_ADMIN_KEY_1": "{}",
   // "USERPREFS_USE_ADMIN_KEY_2": "{}",