Facility location: click-to-pick Neshan map + 'my current location'

- RegisterFacility: '📍 موقعیت فعلی من' (browser geolocation, always available) + Neshan Leaflet map (click/drag marker → fills lat/lng) when a Neshan web key is set; graceful fallback to manual coords without a key
- AppSetting.NeshanMapKey configured in /Admin/Settings (Google Maps is blocked in Iran); migration
- Verified: location button + inputs render always; map + SDK render once the key is saved

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

src/JobsMedical.Web/Models/AppSetting.cs

@@ -62,6 +62,10 @@ public class AppSetting
     /// <summary>Sender line for plain SMS fallback when no template is set.</summary>
     [MaxLength(30)] public string? SmsSender { get; set; }
 
+    /// <summary>Neshan web map.js API key — enables the click-to-pick map on the facility form
+    /// (Google Maps is blocked in Iran). Empty → only the "my location" button is shown.</summary>
+    [MaxLength(200)] public string? NeshanMapKey { get; set; }
+
     public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
 
     /// <summary>Split a textarea (newline/comma separated) into trimmed non-empty items.</summary>