Show the manager's own rate instead of the model's #100

Blocked by: #96, #99

Problem

When the manager sets their own rate for a night, the app should follow their judgement. The recommendations only return the model's rate.

Goal

Wherever a night's rate is shown, the manager's rate is used once they've set one, with the model's rate still available.

Scope

• The recommendations range route and the night detail endpoint return, for each night, the model's rate, the manager's rate if set, and which one to show.
• The manager's rate comes from their latest feedback for that night.
• Removing or changing that feedback updates the rate shown.

Considerations

• Keep the change since the previous snapshot based on the model's rate, so the manager can still see what the model did.
• A newer model rate after the manager's feedback doesn't replace the manager's rate; decide whether to flag that the model has moved since.

Acceptance criteria

• A night with a manager's rate returns it as the rate to show, alongside the model's rate.
• Changing the feedback updates the rate shown.
• Nights without a manager's rate are unchanged.
• Tests cover nights with and without a manager's rate.