Open a night to see why it's priced that way #111

Blocked by: #107

Problem

The manager won't act on a rate they don't understand. They need to see what's driving each night's price to trust or challenge it.

Goal

A night detail page that shows the rate, how sure the model is, the factors behind the price in euros, and the events affecting the night.

Scope

• A page per night, opened from the calendar's "Open day" link, with a link back.
• Show:
  • the rate and the change since the last update;
  • the range the rate is likely to fall in, explained in plain words;
  • the factors that add up to the rate, in € (e.g. "Saturday +€30", "Concert at 3Arena +€45"), starting from the normal rate;
  • the events affecting the night, with venue and "day 2 of 3" for multi-day events;
  • the manager's own rate and latest feedback, if any;
  • when this rate was worked out.
• The feedback form lives on this page.

Design

• No design exists for the full page; only the calendar popover is designed. Design the page before building.
• Factors should read as a simple breakdown a hotel manager understands, biggest first, with small ones grouped as "Other".
• Explain the range without statistics terms (e.g. "most likely between €260 and €300").

Acceptance criteria

• The design is agreed before building.
• The page shows the rate, range, factors and events for a night (against mocks until the backend is ready).
• The factors visibly add up to the rate.
• Multi-day events show which day of the event it is.
• Nights without events or feedback show sensible empty states.