[AZ-371] Refactor C18: magic numbers to ProcessingConfig/MapConfig

Promotes 8 operational levers into config keys with defaults that match
the prior source literals byte-for-byte:
  ProcessingConfig: RegionProcessingTimeoutSeconds (300),
  RouteProcessingPollIntervalSeconds (5),
  MaxRoutePointSpacingMeters (200), LatLonTolerance (0.0001).
  MapConfig: TileSizePixels (256), AllowedZoomLevels ([15..19]),
  RetryBaseDelaySeconds (1), RetryMaxDelaySeconds (30).

Sites updated: RegionService, RouteProcessingService,
RoutePointGraphBuilder, RouteValidator, RouteService 4-arg ctor,
RouteImageRenderer, GoogleMapsDownloaderV2, TileService. Closes LF-2 by
forwarding HttpContext.RequestAborted from GetTileByLatLon into the
downloader. appsettings.json gains the 8 new keys at default values.

Tests: 141 / 141 unit + 5 / 5 smoke green. New ConfigDefaultsTests pins
defaults to original literals; new TileService unit test asserts CT
identity from caller to downloader (AZ-371 AC-3).

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

SatelliteProvider.Tests/InfrastructureTests.cs

@@ -1,7 +1,9 @@
 using FluentAssertions;
 using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 using Moq;
+using SatelliteProvider.Common.Configs;
 using SatelliteProvider.Common.DTO;
 using SatelliteProvider.Common.Interfaces;
 using SatelliteProvider.DataAccess.Models;
@@ -65,7 +67,8 @@ public class InfrastructureTests
         var logger = NullLogger<TileService>.Instance;
 
         // Act
-        var service = new TileService(downloader, tileRepo, cache, logger);
+        var mapConfig = Options.Create(new MapConfig { Service = "GoogleMaps", ApiKey = "" });
+        var service = new TileService(downloader, tileRepo, cache, mapConfig, logger);
 
         // Assert
         service.Should().NotBeNull();