POST/PATCH Site for public API

Added POST /v1/site so integrators can create sites with core details like address, monitoring, notes, client links, terms acceptance, SLA, and owner assignments.

Added PATCH /v1/site/{id} so integrators can update those same core site details on existing sites.

Improved bulk delete reliability so large delete jobs are more predictable and easier to track.

Improved site deletion so related records are handled safely and deleted addresses can be restored later.

Fixed partner export behavior so all expected addresses are included in client-site.json.

Fixed D-Tools and Portal.io imports so contacts without a last name no longer fail import.

Fixed the Day 1 submission flow so missing primary clients no longer cause failures.

Fixed conversation drafts so deleted drafts stay in sync after refresh and across browser tabs.