[AZ-1074] [AZ-1075] gRPC tile stream tests and shared proto

Extract tile_provision.proto into GrpcContracts, add integration
tests and validation hardening for DeliverRouteTiles streaming.

Co-authored-by: Cursor <cursoragent@cursor.com>

SatelliteProvider.Services.RouteManagement/TileProvision/RouteTileDeliveryOrchestrator.cs

@@ -226,6 +226,24 @@ public sealed class RouteTileDeliveryOrchestrator
             throw new ArgumentException("Route must have at least 2 waypoints", nameof(job));
         }
 
+        for (var i = 0; i < job.Waypoints.Count; i++)
+        {
+            var (lat, lon) = job.Waypoints[i];
+            if (lat is < -90.0 or > 90.0)
+            {
+                throw new ArgumentException(
+                    $"waypoints[{i}].lat must be between -90 and 90",
+                    nameof(job));
+            }
+
+            if (lon is < -180.0 or > 180.0)
+            {
+                throw new ArgumentException(
+                    $"waypoints[{i}].lon must be between -180 and 180",
+                    nameof(job));
+            }
+        }
+
         if (job.RegionSizeMeters <= 0)
         {
             throw new ArgumentOutOfRangeException(nameof(job), "region_size_meters must be positive");