- ZipCodeDistance helper with Haversine formula on 33K US zip code centroids
- Loaded as singleton from wwwroot/zipcodes.csv on startup
- Vendor Dropdown endpoint accepts siteZip, returns address and distanceMiles
- Vendors sorted by distance when siteZip provided
- Include locationZip in GetWorkorderById response
- Create Vendor model with company info, trade specialties, active flag
- Create Dispatch model (doubles as Vendor PO) with PO number, NTE, status, reply-to address
- VendorController: CRUD, paginated list, dropdown endpoint with trade filtering
- DispatchToVendor endpoint: multi-vendor dispatch, auto-generated PO numbers (VPO-00001),
HTML email with full WO details via SendGrid, reply-to wo-{number}@int.seahaven.com
- GetDispatches endpoint for listing dispatches by WO
- Include dispatches in GetWorkorderById response
- SendMessage.SendDispatchEmail with reply-to support
- Audit log entry for each dispatch
