[AZ-370] Refactor C17: status / point-type enums + AC RT2 update

Replaces bare strings with two enums in Common/Enums/:
  RegionStatus { Queued, Processing, Completed, Failed }
  RoutePointType { Start, End, Action, Intermediate }

Adds a Dapper EnumStringTypeHandler<T> (DataAccess/TypeHandlers/)
that round-trips enums to/from lowercase strings, registered once
at startup via DapperEnumTypeHandlers.RegisterAll(). DataAccess now
references Common (project ref) so entities can carry the enum types.

Sites converted: RegionService (5), RouteProcessingService (3),
RoutePointGraphBuilder (4), entity Status/PointType columns. Log
message and summary file format preserved via .ToLowerInvariant().

API JSON contract preserved by adding JsonStringEnumConverter with
JsonNamingPolicy.CamelCase to the http JSON options — single-word
enum members serialize to the same lowercase strings as before.

DTO renamed: Common.DTO.RegionStatus -> RegionStatusResponse to
free the RegionStatus name for the new enum (forced by the task's
explicit enum name); the renamed DTO has no public-API impact at
the JSON wire level. Stale doc references updated.

AC RT2 in _docs/00_problem/acceptance_criteria.md now lists all 4
point types (start/end/action/intermediate).

Tests: 171 / 171 unit + 5 / 5 smoke green (was 141 + 5; +30 new tests
covering type handler round-trip, set/parse, unknown-value rejection,
idempotent registration, and the AC RT2 doc check).

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

SatelliteProvider.Common/DTO/RegionStatusResponse.cs

@@ -1,9 +1,11 @@
+using SatelliteProvider.Common.Enums;
+
 namespace SatelliteProvider.Common.DTO;
 
-public class RegionStatus
+public class RegionStatusResponse
 {
     public Guid Id { get; set; }
-    public string Status { get; set; } = string.Empty;
+    public RegionStatus Status { get; set; }
     public string? CsvFilePath { get; set; }
     public string? SummaryFilePath { get; set; }
     public int TilesDownloaded { get; set; }
@@ -11,4 +13,3 @@ public class RegionStatus
     public DateTime CreatedAt { get; set; }
     public DateTime UpdatedAt { get; set; }
 }
-

SatelliteProvider.Common/DTO/RoutePointDto.cs

@@ -1,12 +1,13 @@
+using SatelliteProvider.Common.Enums;
+
 namespace SatelliteProvider.Common.DTO;
 
 public class RoutePointDto
 {
     public double Latitude { get; set; }
     public double Longitude { get; set; }
-    public string PointType { get; set; } = string.Empty;
+    public RoutePointType PointType { get; set; }
     public int SequenceNumber { get; set; }
     public int SegmentIndex { get; set; }
     public double? DistanceFromPrevious { get; set; }
 }
-

SatelliteProvider.Common/Enums/RegionStatus.cs

@@ -0,0 +1,9 @@
+namespace SatelliteProvider.Common.Enums;
+
+public enum RegionStatus
+{
+    Queued,
+    Processing,
+    Completed,
+    Failed,
+}

SatelliteProvider.Common/Enums/RoutePointType.cs

@@ -0,0 +1,9 @@
+namespace SatelliteProvider.Common.Enums;
+
+public enum RoutePointType
+{
+    Start,
+    End,
+    Action,
+    Intermediate,
+}

SatelliteProvider.Common/Interfaces/IRegionService.cs

@@ -4,8 +4,8 @@ namespace SatelliteProvider.Common.Interfaces;
 
 public interface IRegionService
 {
-    Task<RegionStatus> RequestRegionAsync(Guid id, double latitude, double longitude, double sizeMeters, int zoomLevel, bool stitchTiles = false);
-    Task<RegionStatus?> GetRegionStatusAsync(Guid id);
+    Task<RegionStatusResponse> RequestRegionAsync(Guid id, double latitude, double longitude, double sizeMeters, int zoomLevel, bool stitchTiles = false);
+    Task<RegionStatusResponse?> GetRegionStatusAsync(Guid id);
     Task ProcessRegionAsync(Guid id, CancellationToken cancellationToken = default);
 }