[AZ-808] [AZ-811] Strict validation on region POST + lat/lon GET

AZ-808: FluentValidation for POST /api/satellite/request
- RegionRequestValidator: id non-empty, lat/lon/sizeMeters/zoomLevel ranges
- RequestRegionRequest: [JsonRequired] on every property, no implicit defaults
- Wired via .WithValidation<RequestRegionRequest>() in MapPost chain
- Unit + integration tests + curl probe script
- New contract: contracts/api/region-request.md v1.0.0

AZ-811: FluentValidation + envelope filter for GET /api/satellite/tiles/latlon
- GetTileByLatLonQuery: nullable record (double?/int?) so the minimal-API
  binder never short-circuits with BadHttpRequestException before filters
- GetTileByLatLonQueryValidator: Cascade(Stop) + NotNull + InclusiveBetween
  per param; missing surfaces as `\`<name>\` is required.`
- RejectUnknownQueryParamsEndpointFilter: reusable IEndpointFilter that
  rejects any query key outside the allowed set with errors[<key>] map;
  catches legacy `?Latitude=` typos and hostile probes (`?debug=1&admin=1`)
- Handler: [AsParameters] GetTileByLatLonQuery + .Value deref post-validator
- Unit (validator + filter) + integration tests + curl probe script
- New contract: contracts/api/tile-latlon.md v1.0.0

Shared hygiene
- Promote AssertErrorsContainsMention from per-test-file private helpers to
  ProblemDetailsAssertions (closes batch-1 Low-severity DRY warning)
- Sync Swagger param descriptions, README, blackbox/security/perf scripts,
  uuidv5 doc with the new lat/lon/zoom query-param names

Docs
- system-flows.md F1/F2 reference the new contracts + validation layers
- modules/api_program.md adds Api/Validators + Api/DTOs sections
- _autodev_state.md: batch 2 of 4 complete; next batch = AZ-809

All smoke tests green (mode=smoke, exit 0). AZ-808 + AZ-811 transitioned
to In Testing on Jira.

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

SatelliteProvider.Api/Swagger/ParameterDescriptionFilter.cs

@@ -11,13 +11,11 @@ public class ParameterDescriptionFilter : IOperationFilter
 
         var parameterDescriptions = new Dictionary<string, string>
         {
-            ["lat"] = "Latitude coordinate where image was captured",
-            ["lon"] = "Longitude coordinate where image was captured",
+            ["lat"] = "Latitude coordinate (WGS84, decimal degrees, [-90, 90])",
+            ["lon"] = "Longitude coordinate (WGS84, decimal degrees, [-180, 180])",
+            ["zoom"] = "Slippy-map zoom level [0, 22] (higher = more detail)",
             ["mgrs"] = "MGRS coordinate string",
-            ["squareSideMeters"] = "Square side size in meters",
-            ["Latitude"] = "Latitude coordinate of the tile center",
-            ["Longitude"] = "Longitude coordinate of the tile center",
-            ["ZoomLevel"] = "Zoom level for the tile (higher values = more detail)"
+            ["squareSideMeters"] = "Square side size in meters"
         };
 
         foreach (var parameter in operation.Parameters)