Initial commit — Hamkadr (همکادر) healthcare-staffing marketplace

ASP.NET Core 10 Razor Pages + PostgreSQL/EF Core. RTL Persian, Jalali dates, self-hosted Vazirmatn, teal/coral brand.

Features:
- Shift listings: browse/filter (city, district, role, type, pay), weekly Jalali calendar, detail + interest handoff, near-me distance sort
- Hiring (استخدام) listings with employment type + salary range
- Pattern-engine recommendations + anonymous interest tracking (visitor cookie)
- Heuristic Persian listing-parser + admin queue (raw channel post → shift/job)
- Phone-OTP cookie auth + visitor-history linking + profile

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/JobsMedical.Web/Services/Geo.cs

@@ -0,0 +1,19 @@
+namespace JobsMedical.Web.Services;
+
+public static class Geo
+{
+    private const double EarthRadiusKm = 6371.0;
+
+    /// <summary>Great-circle (Haversine) distance in kilometers between two lat/lng points.</summary>
+    public static double DistanceKm(double lat1, double lng1, double lat2, double lng2)
+    {
+        double dLat = ToRad(lat2 - lat1);
+        double dLng = ToRad(lng2 - lng1);
+        double a = Math.Sin(dLat / 2) * Math.Sin(dLat / 2)
+                 + Math.Cos(ToRad(lat1)) * Math.Cos(ToRad(lat2))
+                 * Math.Sin(dLng / 2) * Math.Sin(dLng / 2);
+        return EarthRadiusKm * 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
+    }
+
+    private static double ToRad(double deg) => deg * Math.PI / 180.0;
+}