Creates a new solar financing qualification application for a customer.

Business Context:
This is the first step in the solar financing workflow. The application collects
customer demographic and contact information needed for credit qualification.

Required Information:

• Primary applicant details (name, address, contact, SSN last 4 digits)
• Product and agreement type for the solar installation
• Sales team assignment (dealer, installer, sales rep)
• Customer consents for credit checks and terms

Optional Information:

• Co-applicant details (joint applications for better qualification)
• External identifiers for integration with your systems
• Reference ID (e.g., proposal or quote ID)

Next Steps:
After creation, applications start in open status. You must call the submit endpoint
before running qualification checks.