Phase 2: rental form now has optional Owner and Unit selectors (auto-fills
renter info/unit from the chosen owner), persisting owner_id/unit_id.
Phase 3: add RvRentalVacateButton on Owner and Unit profiles — shows only
when that owner/unit has an active/vacating RV-boat rental, and toggles the
rental status between active (renting) and vacating. Active Rentals tab now
includes vacating rentals with a badge.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>