fix(matchmaking): select the relative best two-person match

[Ltcc0]

Summary

• treat acceptable groups as valid candidates instead of rejecting them at an absolute quality gate
• keep bad groups excluded while ranking acceptable below good and excellent
• apply the same rule to round offers, open-room joins, and final settlement
• add an end-to-end two-person regression covering offer and room creation

Verification

• pnpm --filter @tomeet/intelligence typecheck
• pnpm --filter @tomeet/intelligence test (60 passed)