PM-6312: Correct current Marathon Match test process

[jmgasper]

Related JIRA Ticket:

https://topcoder.atlassian.net/browse/PM-6312

What’s in this PR?

• infer the temporary Marathon Match scorer stage from an unambiguous current/open challenge phase while the first summation is pending
• keep explicit scorer evidence authoritative and avoid guessing during mixed or unknown phases
• add regression coverage for the recorded Submission-phase race, Review phase, phase aliases, and ambiguous overlaps
• document the scorer lifecycle behavior

Validation

• yarn test:no-watch --runInBand src/apps/opportunities/src/utils/marathon-match.utils.spec.ts
• yarn test:no-watch --runInBand src/apps/opportunities/src/pages/ChallengeDetailsPage.flows.spec.tsx -t "renders Marathon Match testing progress"
• yarn lint
• yarn tsc --noEmit
• NODE_OPTIONS=--max-old-space-size=8192 yarn build
• git diff --check