Show project and billing history in Sales opportunity modal -> dev

[jmgasper]

Related JIRA Ticket

Not provided.

What's in this PR?

The Sales opportunity modal now shows the current billing account ID/name, an environment-specific Work link to /projects/{projectId}/challenges, and a list of past billing account IDs/names supplied by the Projects API.

All new fields are hidden when the opportunity has no billing account. The current account is omitted from the past-account list, an empty history has an explicit empty state, and unresolved names retain their IDs. A missing project does not produce a Work link. Includes URL validation, modal regression tests, and documentation.

Validation

• yarn lint passed.
• NODE_OPTIONS=--max-old-space-size=8192 yarn run build passed with existing warnings. The clean build exceeded Node's default 4 GB heap limit, so validation used an 8 GB limit.
• Sales tests: 35 passed across four suites.

Dependencies and deployment

Deploy in this order:

1. Add Salesforce opportunity filter for billing accounts billing-accounts-api-v6#29
2. Add project billing history to Salesforce opportunity details projects-api-v6#52
3. This PR.