Fix extraneous room key in WCIF PATCH payload

[Copilot]

• Identified root cause: updateRoundActivities reducer stores ActivityWithRoom objects (with room property) directly into WCIF state, causing invalid WCIF schema when sent to the API
• Fixed updateRoundActivities reducer to strip room (and any other extraneous) properties when storing activities into WCIF
• Updated existing test and added regression test for the room stripping
• Fixed pre-existing test failure in actions.test.ts (always-send-version)
• Fixed CI: lint.yml and type-check.yml were pinning node-version: '18', but @vitejs/plugin-react@5.1.2 requires ^20.19.0 || >=22.12.0. Updated both to use node-version-file: '.nvmrc' (consistent with test.yml)
• All 350 tests passing, lint clean, typecheck clean

[coder13]

@copilot fix lint and typecheck issues

[Copilot]

@copilot fix lint and typecheck issues

The CI failures were caused by lint.yml and type-check.yml hard-coding node-version: '18', but @vitejs/plugin-react@5.1.2 requires Node ^20.19.0 || >=22.12.0. Updated both workflows to use node-version-file: '.nvmrc' (consistent with test.yml) in commit a7dfbc8.