Fix crash when peer has nil publicKey in site config

Skip sites with empty/nil publicKey instead of passing them to the
WireGuard UAPI layer, which expects a valid 64-char hex string. A nil
key occurs when a Newt site has never connected. Previously this caused
all sites to fail with "hex string does not fit the slice".

olm/connect.go

@@ -172,6 +172,12 @@ func (o *Olm) handleConnect(msg websocket.WSMessage) {
 
 	for i := range wgData.Sites {
 		site := wgData.Sites[i]
+
+		if site.PublicKey == "" {
+			logger.Warn("Skipping site %d (%s): no public key available (site may not be connected)", site.SiteId, site.Name)
+			continue
+		}
+
 		var siteEndpoint string
 		// here we are going to take the relay endpoint if it exists which means we requested a relay for this peer
 		if site.RelayEndpoint != "" {

olm/peer.go

@@ -37,6 +37,11 @@ func (o *Olm) handleWgPeerAdd(msg websocket.WSMessage) {
 		return
 	}
 
+	if siteConfig.PublicKey == "" {
+		logger.Warn("Skipping add-peer for site %d (%s): no public key available (site may not be connected)", siteConfig.SiteId, siteConfig.Name)
+		return
+	}
+
 	_ = o.holePunchManager.TriggerHolePunch() // Trigger immediate hole punch attempt so that if the peer decides to relay we have already punched close to when we need it
 
 	if err := o.peerManager.AddPeer(siteConfig); err != nil {