8 pure helpers (normalizeAutoRecordPollSeconds, normalizeAutoRecordList,
normalizeStreamlinkQuality, normalizeFilenameTemplate,
normalizeMetadataCacheMinutes, normalizePerformanceMode, isPlainObject,
normalizeLogin) plus VALID_STREAMLINK_QUALITIES + PerformanceMode type.
getStreamlinkStreamArg and normalizeConfigTemplates stay in main.ts
because they read globals (config / DEFAULT_*).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
