Add and edit guests

A real person enters what they know and comes back later. The form must not demand more than a name and a side.

Acceptance criteria

• Slide-over panel from the right, dimmed page behind. Same panel serves add and edit
• Thirteen fields in the five groups shown in KB-6
• Only name and side are required
• partnerOf is a picker over existing guests, and setting it sets the reciprocal side
• conflictsWith is a multi-picker, also reciprocal
• Tags entered as pills, autocompleting against tags already in use
• Allergies and dietary preferences are separate fields and never merged
• Save closes the panel and briefly highlights the row
• Deleting a guest clears them from any reciprocal relationship and from any plan