Letter of Credit schema (KTDDE Batch 2)
Adds the Letter of Credit (LC) as a Verifiable Credential schema, covering all 18 KTDDE elements with 0 mandatory gaps.
Registers LC in the compliance script and updates manual mappings with new documentary-credit UIDs (2211, 2237, 3150, 3198, 3234, 3242, 3260, 3290, 3350, 5450) and per-document entries for 3000, 3356, and 7002.