Resolves Issue #1715, Add expanded user map to registry org response

[afoote-mitre]

Closes Issue #1715

Summary

Adds optional expanded user metadata to the single registry organization response via expand=users, reducing the need for clients to fetch all orgs/users just to resolve UUIDs in org views.

Important Changes

src/controller/org.controller/index.js

• Allows expand=users on GET /api/registry/org/{identifier}
• Documents the new query parameter in Swagger annotations

src/controller/org.controller/org.middleware.js

• Maps the expand query parameter into req.ctx.query

src/controller/registry-org.controller/registry-org.controller.js

• Adds _userMap hydration when expand=users is requested
• Builds the map from org users, admins, defensive contact_info.additional_contacts, and visible conversation author_ids

src/repositories/baseUserRepository.js

• Adds batch lookup for users by UUID

src/repositories/baseOrgRepository.js

• Adds batch lookup for orgs containing user UUIDs

schemas/registry-org/get-registry-org-response.json

• Documents the _userMap response object

api-docs/openapi.json

• Adds expand query parameter documentation for the registry org lookup endpoint

test/unit-tests/org/registryOrgGetSingleTest.js

• Adds unit coverage for default response behavior and expand=users

test/integration-tests/registry-org/registryOrgCRUDTest.js

• Adds integration coverage for expanded user metadata on a registry org response

Testing

Steps to manually test updated functionality:

• 1) Call GET /api/registry/org/{shortname} and verify _userMap is not present
• 2) Call GET /api/registry/org/{shortname}?expand=users and verify _userMap is present
• 3) Verify _userMap is keyed by user UUID and includes username, name, and org.short_name
• 4) Add or find a conversation on the org and verify visible conversation author UUIDs are included in _userMap
• 5) Call GET /api/registry/org/{shortname}?expand=invalid and verify the request is rejected

Recommended automated tests:

• npm run test:integration
• npm run test:unit-tests

Notes

• _userMap is returned as an object keyed by UUID
• contact_info.additional_contacts is handled defensively, but it is not currently modeled as a first-class registry org schema field