Shutter speed improvements

You can now define shutter speed step increments for each camera, choosing between full, half, or third stops, along with a minimum and maximum range. This matches the same approach already available for aperture on lenses.

The shutter speed picker in frame editing and in the toolbar now only displays values that match your camera settings. This makes it easier to work with different gear without seeing unsupported values.

Before this change, shutter speeds were based on a fixed list. Some cameras, such as the Nikon F3, required additional values that were not included. This update replaces that fixed approach with a flexible system that covers industry-standard ranges more reliably.

Custom shutter speed sequences are still supported for users with specific or less common setups.

This update comes from a user suggestion. Feedback like this continues to shape Frames over time and helps improve how the app fits real-world shooting setups.