[AZ-812] Region API: rename Latitude/Longitude → Lat/Lon (OSM convention)

Mirror of AZ-794 (inventory z/x/y rename). RequestRegionRequest.cs renames C#
props Latitude→Lat / Longitude→Lon and adds [JsonPropertyName("lat"/"lon")] so
the wire format is unambiguous under the AZ-795 strict-parsing stack
(UnmappedMemberHandling.Disallow → legacy {"latitude":..,"longitude":..} now
returns HTTP 400 instead of silently coercing).

Updates all in-repo consumers: API handler (Program.cs), integration tests
(Models.cs, RegionTests.cs, IdempotentPostTests.cs, SecurityTests.cs), the
performance harness (run-performance-tests.sh PT-03/04/05/07), and module
docs (common_dtos.md, api_program.md; system-flows.md F2 already used
lat/lon). New RegionFieldRenameTests.cs covers AC-4 both directions (new
format → 200, legacy format → 400). Smoke green; no regressions.

region-request.md contract doc not bumped here — AZ-808 publishes v1.0.0
directly with the post-rename names per AZ-812 coordination clause.

Batch 01 of cycle 8. PASS_WITH_WARNINGS (one Low DRY finding for follow-up
test-helper consolidation; details in
_docs/03_implementation/reviews/batch_01_cycle8_review.md).

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

_docs/02_document/modules/api_program.md

@@ -21,9 +21,11 @@ Application entry point. Configures DI container, sets up middleware, defines mi
 ### Local Records (defined in Program.cs)
 - `GetSatelliteTilesResponse`, `SatelliteTile` — MGRS response stubs
 - `DownloadTileResponse` — tile download response
-- `RequestRegionRequest` — region request body
 - `ParameterDescriptionFilter` — Swagger operation filter
 
+### Common/DTO (region API)
+- `RequestRegionRequest` — `POST /api/satellite/request` body. Moved out of Program.cs by AZ-369. Fields: `Id` (Guid), `Lat`/`Lon` (double, JSON `lat`/`lon` per AZ-812 cycle 8 OSM rename), `SizeMeters`, `ZoomLevel` (int, default 18), `StitchTiles` (bool, default false).
+
 ### Api/DTOs (AZ-488)
 - `UavTileBatchUploadRequest` — multipart envelope with `metadata` (JSON string) and `files` (`IFormFileCollection`)
 

_docs/02_document/modules/common_dtos.md

@@ -33,8 +33,14 @@ Metadata about a stored tile (mirrors `TileEntity` but without DB-specific conce
 - `Version` (int?), `FilePath` (string)
 - `CreatedAt`, `UpdatedAt` (DateTime)
 
+### RequestRegionRequest (renamed by AZ-812 cycle 8 — OSM convention)
+API request body for `POST /api/satellite/request` (region enqueue). Defined in `SatelliteProvider.Common/DTO/RequestRegionRequest.cs`. Moved out of `Program.cs` by AZ-369.
+- `Id` (Guid), `Lat` (double, JSON: `"lat"`), `Lon` (double, JSON: `"lon"`), `SizeMeters` (double)
+- `ZoomLevel` (int, default 18), `StitchTiles` (bool, default false)
+- AZ-812 renamed C# props `Latitude/Longitude` → `Lat/Lon` and added `[JsonPropertyName("lat")]` / `[JsonPropertyName("lon")]` to make the wire format unambiguous. With `JsonSerializerOptions.UnmappedMemberHandling.Disallow` active (AZ-795), the old `latitude`/`longitude` wire shape now returns HTTP 400.
+
 ### RegionRequest
-Queue message for async region processing.
+Internal queue message for async region processing (not a wire-format DTO — exchanged between the API handler and `RegionProcessingService` background worker via `IRegionRequestQueue`). Distinct from `RequestRegionRequest` above; intentionally kept on `Latitude`/`Longitude` because the queue is in-process only.
 - `Id` (Guid), `Latitude`, `Longitude` (double), `SizeMeters` (double)
 - `ZoomLevel` (int), `StitchTiles` (bool)