fix(coworld): distinguish active champion from rating row

[0xNad]

What changed

• fetches active Coworld champion memberships separately from leaderboard results
• preserves the historical results.policy_label as rating-row provenance
• displays the active champion and rating row independently when they differ
• preserves the legacy policyLabel field for existing data.json consumers
• keeps mirror publishing when membership lookup is unavailable

Why

The public league page showed proxywar-keystone:v7 as Auri's running version even though live Coworld episodes were executing proxywar-keystone:v40. The results API retains the policy label attached to the historical rating row, so treating that label as the active champion was misleading.

Validation

• 23 focused mirror/site tests
• 3 translation-system tests
• TypeScript typecheck
• focused ESLint
• production build
• live read-only Coworld smoke render
• independent review with no remaining findings