S10: Berth booking and tenant self-service

[xishell]

Persona

Visiting boater + Berth tenant + Harbor master

User outcome

As a visiting boater, I reserve a free berth online before arriving so I am not searching a full harbor. As a berth tenant leaving on a trip, I mark my berth available and set a return date so visitors can use it and I know it will be free when I return.

Turns the harbor into a reservable resource. Visitors get guaranteed spots; tenants get goodwill or revenue from their empty slot.

Acceptance Criteria

• Tenant can mark berth available + set return date via the dashboard
• Visitor can see and book available berths
• Overlapping confirmed bookings for the same berth are rejected
• Active bookings appear on the map with a distinct color
• Tenant gets notified of approaching return date