PM-6307 Cover multiple Design checkpoint submissions -> dev

[jmgasper]

Related JIRA Ticket

PM-6307

What's in this PR?

A two-round Design challenge allowing two submissions shows only the latest submission to its checkpoint screener, leaving an older pending scorecard inaccessible. The root cause is the Review API submission-history privacy filter. The required runtime fix is review-api-v6 PR #344, which must be merged and deployed to resolve the reported bug.

This frontend companion adds regression coverage through the real checkpoint tab, role hook, and table column renderers at desktop and mobile widths. It verifies that both submissions from a member remain visible, the older pending row links to its own scorecard, and progress remains 67% when two of three screenings are complete. The Review README documents the API visibility contract.

Validation:

• yarn lint passed.
• NODE_OPTIONS=--max-old-space-size=8192 yarn run build passed with existing dependency source-map and bundle-size warnings.
• Targeted checkpoint table and progress suites: 10 tests passed.
• Node 22.13.0 selected using nvm use.

Branch PM-6307 was created from origin/dev at 363f4d08f.