fix(node): bound the panel GUIDs a peer reports

A peer's panelGuid is copied into nodes.guid and into every inbound row
it reports (an indexed column), a forwarded origin GUID likewise, and a
GUID-keyed IP tree or a master's global-traffic push keys one row per
client. One oversized value therefore multiplied into gigabytes stored.
GUIDs over 64 bytes (panels mint 36-character UUIDs) now fail the
heartbeat, fall back to the reporting node's key, or are dropped.

internal/web/service/inbound_node_ips.go

@@ -139,6 +139,10 @@ func (s *InboundService) MergeClientIpsByGuid(node *model.Node, trees map[string
 		}
 	}
 	for guid, perEmail := range trees {
+		// Stored once per email: an oversized key would multiply into every row.
+		if len(guid) > maxPanelGuidLen {
+			continue
+		}
 		if err := upsertNodeClientIps(guid, perEmail); err != nil {
 			return err
 		}