[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.Tests/RouteTileDeliveryOrchestratorTests.cs

@@ -15,6 +15,28 @@ namespace SatelliteProvider.Tests;
 
 public class RouteTileDeliveryOrchestratorTests
 {
+    [Fact]
+    public async Task DeliverAsync_InvalidLatitude_Throws()
+    {
+        var expander = new RouteTileExpander(
+            new RoutePointGraphBuilder(Options.Create(new ProcessingConfig { MaxRoutePointSpacingMeters = 200 })),
+            new GeofenceGridCalculator());
+        var orchestrator = CreateOrchestrator(expander, Mock.Of<ITileRepository>(), Mock.Of<ITileService>());
+        var job = new RouteTileDeliveryJob(
+            Guid.NewGuid(),
+            [(91.0, 37.0), (47.0, 37.0)],
+            400,
+            18,
+            [],
+            false,
+            []);
+
+        var act = () => orchestrator.DeliverAsync(job, new RecordingSink(), CancellationToken.None);
+
+        await act.Should().ThrowAsync<ArgumentException>()
+            .WithMessage("*lat must be between -90 and 90*");
+    }
+
     [Fact]
     public async Task DeliverAsync_AllTilesSkippedByClient_EmitsManifestAndCompleteWithZeroDelivered()
     {
@@ -160,6 +182,21 @@ public class RouteTileDeliveryOrchestratorTests
         }
     }
 
+    private static RouteTileDeliveryOrchestrator CreateOrchestrator(
+        RouteTileExpander expander,
+        ITileRepository tileRepo,
+        ITileService tileService)
+    {
+        return new RouteTileDeliveryOrchestrator(
+            expander,
+            tileRepo,
+            tileService,
+            Options.Create(new MapConfig { TileSizePixels = 256, AllowedZoomLevels = [18] }),
+            Options.Create(new ProcessingConfig { MaxConcurrentDownloads = 2 }),
+            Options.Create(new TileProvisionConfig { MaxTilesPerBatch = 100 }),
+            NullLogger<RouteTileDeliveryOrchestrator>.Instance);
+    }
+
     private sealed class RecordingSink : IRouteTileDeliverySink
     {
         public (uint Total, uint Skipped, uint ToDeliver)? Manifest { get; private set; }