Adds EnvelopeCreateResult inner DTO and createEnvelope(Id, String, String)
to DocusignESignatureService. Option A (template-based): POSTs to
/v2.1/accounts/{accountId}/envelopes with templateId, templateRoles
(Signer), and status=sent. Guards blank templateId and blank appraiser
email; catches all exceptions and wraps in result. Named credential
sourced from CLM_Account_Setting__mdt per ADR-002.
Agent: claude-sonnet-4-6
Tests: 8/8 passing | N/A (no new test methods — Task 3 covers test coverage)
Tests-Added: 0
TypeScript: N/A (Apex project)
c3421e858f