Router: demote cross-channel decrypt failures from ERROR to DEBUG (#10259)

The "Invalid protobufs (bad psk?)" and "Invalid portnum (bad psk?)"
messages fire every time a neighbor transmits on a channel whose
8-bit hash matches one of ours but the PSK differs. In RF environments
with multiple mesh groups nearby this is routine — a single device
can see dozens of these per minute from SAR/MeshCA/private networks
sharing a hash collision.

LOG_ERROR for a benign "not our PSK" event:
- spams the log when you have any neighboring mesh group
- makes a genuine PSK misconfiguration on YOUR own channel
  indistinguishable from the constant cross-channel noise
- hides actual errors in the stream

LOG_DEBUG matches how similar decryption-failure paths are handled
elsewhere (eg. the PKC "decrypt attempted but failed" uses LOG_WARN).
Dropping the trailing "!" as well — these are expected events, not
exceptional ones.

src/mesh/Router.cpp

@@ -499,9 +499,9 @@ DecodeState perhapsDecode(meshtastic_MeshPacket *p)
                 meshtastic_Data decodedtmp;
                 memset(&decodedtmp, 0, sizeof(decodedtmp));
                 if (!pb_decode_from_bytes(bytes, rawSize, &meshtastic_Data_msg, &decodedtmp)) {
-                    LOG_ERROR("Invalid protobufs in received mesh packet id=0x%08x (bad psk?)!", p->id);
+                    LOG_DEBUG("Invalid protobufs in received mesh packet id=0x%08x (bad psk?)", p->id);
                 } else if (decodedtmp.portnum == meshtastic_PortNum_UNKNOWN_APP) {
-                    LOG_ERROR("Invalid portnum (bad psk?)!");
+                    LOG_DEBUG("Invalid portnum (bad psk?)");
 #if !(MESHTASTIC_EXCLUDE_PKI)
                 } else if (!owner.is_licensed && isToUs(p) && decodedtmp.portnum == meshtastic_PortNum_TEXT_MESSAGE_APP) {
                     LOG_WARN("Rejecting legacy DM");