docs/blueprints: referral manager v1

[VinozzZ]

What:

design doc for referral manager v1

Why:

Due to business requirement changes, we need to pivot from the previous design.

Please describe the tests:

• Test 1:
• Test 2:

Please describe the performance impact:

Code Review Checklist (to be filled out by reviewer)

• Does the PR describe what changes are being made?
• Does the PR describe why the changes are being made?
• Does the code follow our style guide?
• Does the code follow our testing guide?
• Is the PR appropriately sized? (If it could be broken into smaller PRs it should be)
• Does the new code have enough tests? (every PR should have tests or justification otherwise. Bug-fix PRs especially)
• Does the new code have enough documentation that answers "how do I use it?" and "what does it do?"? (both source documentation and higher level, diagrams?)
• Does any documentation need updating?
• Do the database access patterns make sense?

[egonelbre]

looks good

[jtolio]

looks great! great work! i didn't review the pseudocode, but i definitely echo paul's sentiments about making sure to use transactions