[AZ-351][AZ-352][AZ-363] Refactor 03 batch 1: critical defensive fixes

AZ-351: Resolve ILogger<DatabaseMigrator> directly from DI in
Program.cs instead of casting ILogger<Program> (which always
returned null). Migrator now logs through Serilog at startup.

AZ-352: Drop empty catch in
RouteProcessingService.ExtractTileCoordinatesFromFilename. Convert
the method from private static to internal instance so it can use
the existing _logger (per coderule: side-effecting code must not be
static). Add typed null-guard via ArgumentNullException.ThrowIfNull
so unexpected exceptions propagate. Adds InternalsVisibleTo on the
RouteManagement csproj for SatelliteProvider.Tests, plus 4 unit
tests in RouteProcessingServiceTests.cs covering AC-1 (valid /
malformed / non-numeric) and AC-2 (null path propagation).

AZ-363: Delete _totalEnqueued / _totalDequeued fields and the two
non-atomic ++ writes in RegionRequestQueue. Fields were write-only
dead code and a thread-safety hazard.

Tests: 44/44 unit + 5/5 smoke (scripts/run-tests.sh --smoke).
Code review verdict: PASS, 0 findings, 0 auto-fix attempts.
Batch report: _docs/03_implementation/batch_07_report.md.

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

SatelliteProvider.Api/Program.cs

@@ -79,8 +79,8 @@ builder.Services.AddSwaggerGen(c =>
 
 var app = builder.Build();
 
-var logger = app.Services.GetRequiredService<ILogger<Program>>();
-var migrator = new DatabaseMigrator(connectionString, logger as ILogger<DatabaseMigrator>);
+var migratorLogger = app.Services.GetRequiredService<ILogger<DatabaseMigrator>>();
+var migrator = new DatabaseMigrator(connectionString, migratorLogger);
 if (!migrator.RunMigrations())
 {
     throw new Exception("Database migration failed. Application cannot start.");