Replaces the DocuSign OAuth redirect flow with a direct JWT grant call
using credentials already in .env (same as the CLI). Clicking
"Connect DocuSign" now calls GET /api/auth/docusign/connect which calls
get_access_token() and stores the result in the session cookie.
No email sign-in required.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>