Add formatAperture(_:) helper that emits "f/2", "f/2.5", "f/2.83" instead of "f/2.0", "f/2.50", etc. GrainExif gains a formattedFNumber computed property that re-parses the server-supplied string and routes it through the helper, so settingsLine and any consumer using settingsLine picks up the trimmed format automatically.