[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.GrpcContracts/tile_provision.proto

@@ -0,0 +1,95 @@
+syntax = "proto3";
+
+package satellite.v1;
+
+import "google/protobuf/timestamp.proto";
+
+option csharp_namespace = "Satellite.V1";
+
+service RouteTileDelivery {
+  rpc DeliverRouteTiles(DeliverRouteTilesRequest) returns (stream RouteTileEvent);
+}
+
+message DeliverRouteTilesRequest {
+  RouteSpec route = 1;
+  repeated ClientTileRecord client_tiles = 2;
+}
+
+message RouteSpec {
+  string route_id = 1;
+  repeated Waypoint waypoints = 2;
+  double region_size_meters = 3;
+  int32 zoom = 4;
+  repeated GeofencePolygon geofences = 5;
+  bool include_geofence_tiles = 6;
+}
+
+message Waypoint {
+  double lat = 1;
+  double lon = 2;
+}
+
+message GeofencePolygon {
+  repeated Waypoint vertices = 1;
+}
+
+message ClientTileRecord {
+  int32 z = 1;
+  int32 x = 2;
+  int32 y = 3;
+  double resolution_m_per_px = 4;
+  google.protobuf.Timestamp captured_at = 5;
+  optional string source = 6;
+  bytes content_sha256 = 7;
+}
+
+message RouteTileEvent {
+  oneof payload {
+    RouteManifest manifest = 1;
+    TileBatch batch = 2;
+    ProgressUpdate progress = 3;
+    DeliveryComplete complete = 4;
+    DeliveryError error = 5;
+  }
+}
+
+message RouteManifest {
+  uint32 total_candidates = 1;
+  uint32 skipped_by_client = 2;
+  uint32 to_deliver = 3;
+}
+
+message TileBatch {
+  uint32 batch_seq = 1;
+  repeated TilePayload tiles = 2;
+}
+
+message TilePayload {
+  int32 z = 1;
+  int32 x = 2;
+  int32 y = 3;
+  double resolution_m_per_px = 4;
+  google.protobuf.Timestamp captured_at = 5;
+  string source = 6;
+  bytes jpeg = 7;
+  bytes content_sha256 = 8;
+  uint32 route_priority = 9;
+}
+
+message ProgressUpdate {
+  uint32 delivered = 1;
+  uint32 total = 2;
+  uint32 downloading = 3;
+}
+
+message DeliveryComplete {
+  uint32 delivered = 1;
+  uint32 skipped_client = 2;
+  uint32 skipped_server_filter = 3;
+}
+
+message DeliveryError {
+  string code = 1;
+  string message = 2;
+  bool retryable = 3;
+}