PM-6599: Restore Marathon Match submission ranks

[jmgasper]

What was broken

Marathon Match All Submissions was missing the Final Rank and Provisional Rank columns shown on the old platform.

Root cause

The Opportunities table rendered scores without calculating ranks. Its default date ordering fetched individual pages, which cannot produce challenge-wide rankings.

What was changed

• Add sortable Final Rank and Provisional Rank columns only to Marathon Match All Submissions, with mobile labels and sort options.
• Rank the complete latest-submission collection before sorting and pagination. Reuse the existing score resolver and final-score release gate; missing or pending scores remain unranked.
• Match community-app: provisional ties favor earlier submission times, while equal final scores share competition ranks (1, 1, 3).
• Adjust the eight-column layout and table-card scrolling, and update the Opportunities README.

Files changed: ChallengeDetailsPage.tsx, ChallengeDetailsPage.module.scss, ChallengeDetailsPage.flows.spec.tsx, marathon-match.utils.ts, marathon-match.utils.spec.ts, and src/apps/opportunities/README.md.

Any added/updated tests

• Add 10 regression cases covering score ties, missing/pending scores, summation precedence, both rank-sort directions, global pagination, mobile sorting, final-rank release timing, and non-MM exclusions. Extend My Submissions coverage to verify that its columns stay unchanged.
• Run nvm use before all Node/Yarn commands.
• yarn lint: passed.
• NODE_OPTIONS=--max-old-space-size=12288 yarn run build: passed with existing repository warnings. The initial default-heap build exhausted Node's heap.
• yarn test:no-watch --runInBand src/apps/opportunities: all 713 tests in 61 suites passed.
• yarn test:no-watch --runInBand: 387 suites and 2,736 tests passed; 22 suites failed, including 19 failed tests. The identical failing suites and test cases reproduce on untouched origin/dev (2,726 passing tests). These existing failures include module-resolution, mocks, and unrelated expectation failures and require separate fixes.
• Fixture-backed Chromium checks at 1440px, 1024px, and 390px: rank values, sorting, responsive rendering, and no viewport overflow passed; screenshots inspected.