Allow percentage-based price overrides for specific dates in Dynamic Pricing

Problem: Currently, to override dynamic pricing for a specific date, users must either enter a fixed price or create and apply a pricing rule. There is no way to simply apply a percentage increase or decrease to the dynamically generated price for a single date.

Current Workaround: Users must create a rule and apply it to the specific date, which is a cumbersome and time-consuming process for quick adjustments.

Impact: This creates operational friction and makes it slower for hosts to make tactical pricing adjustments for specific dates.

Proposed Solution: Add the ability to override a specific date's price by a percentage (e.g., +10% or -15%) directly on the calendar.

Unlock: Hosts will be able to make quick, relative pricing adjustments to specific dates without the overhead of creating full rules.