[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.Api/Program.cs

@@ -6,6 +6,7 @@ using SatelliteProvider.Api.DTOs;
 using SatelliteProvider.Api.Swagger;
 using SatelliteProvider.DataAccess;
 using SatelliteProvider.DataAccess.Repositories;
+using SatelliteProvider.DataAccess.TypeHandlers;
 using SatelliteProvider.Common.Configs;
 using SatelliteProvider.Common.DTO;
 using SatelliteProvider.Common.Interfaces;
@@ -22,6 +23,8 @@ builder.Host.UseSerilog((context, configuration) =>
 var connectionString = builder.Configuration.GetConnectionString("DefaultConnection") 
     ?? throw new InvalidOperationException("Connection string 'DefaultConnection' not found.");
 
+DapperEnumTypeHandlers.RegisterAll();
+
 builder.Services.Configure<MapConfig>(builder.Configuration.GetSection("MapConfig"));
 builder.Services.Configure<StorageConfig>(builder.Configuration.GetSection("StorageConfig"));
 builder.Services.Configure<ProcessingConfig>(builder.Configuration.GetSection("ProcessingConfig"));
@@ -58,6 +61,8 @@ builder.Services.ConfigureHttpJsonOptions(options =>
 {
     options.SerializerOptions.PropertyNamingPolicy = System.Text.Json.JsonNamingPolicy.CamelCase;
     options.SerializerOptions.PropertyNameCaseInsensitive = true;
+    options.SerializerOptions.Converters.Add(
+        new System.Text.Json.Serialization.JsonStringEnumConverter(System.Text.Json.JsonNamingPolicy.CamelCase));
 });
 
 builder.Services.AddEndpointsApiExplorer();