Nine KTDDE Batch 2 document schemas

Adds Letter of Credit (LC), Air Waybill (AW), Sea Waybill (SW), Road Consignment Note (CMR), Rail Consignment Note (CIM), Ship's Delivery Order (SDO), Payment Confirmation (PC), Customs Bond (CB), and Dangerous Goods Declaration (DGD) as Verifiable Credential schemas.

All 9 documents have 0 mandatory KTDDE gaps. Combined mappings resolve the per-document conflicts that would arise from merging the 9 individual feature branches independently.