WCIF v1.1: support Best-of-5 (format '5') rounds (3BLD change)

[coder13]

WCIF spec recently moved to v1.1 (notably: 3x3 Blindfolded is now Best of 5).

DelegateDashboard has its own round format mapping in src/lib/domain/events.ts:

• roundFormats includes a/ m /3/2/1 but does not include format id 5.
• Downstream, roundFormatById() is used in src/lib/wcif/persons.ts and elsewhere to decide whether to read result.average vs result.best.
• With WCIF v1.1 competitions, any round with format: "5" (Best of 5) will cause roundFormatById() to return undefined, which breaks seed/result lookups and likely some UI/exports.

Reference: thewca/wca-helpers PR “Wcif 1.1 updates” explicitly calls out “3bld is now best of 5” and updates their RoundFormat handling:
thewca/wca-helpers#47

Acceptance criteria

• Add round format id: "5" with appropriate labels (e.g., short bo5, long Best of 5, rankingResult single).
• Add/update unit tests in src/lib/domain/events.test.ts (and any others) to cover roundFormatById("5") and roundFormatShortById("5").
• Verify any logic that depends on format IDs still works (seed results, result rendering, import/export, validation).

Nice to have

• Audit other WCIF-v1.1-related changes (if any) and update mocks in wcif tests to use formatVersion: "1.1" where relevant.