[AZ-810] Strict validation for POST /api/satellite/upload metadata

Adds the per-endpoint child of AZ-795 ("Strict Input Validation Epic")
for the UAV upload multipart endpoint. Three new validators land under
SatelliteProvider.Api/Validators/:

- UavTileBatchMetadataPayloadValidator: items NotNull + NotEmpty +
  count <= MaxBatchSize + RuleForEach dispatching to the per-item
  validator.
- UavTileMetadataValidator: lat / lon / tileZoom range, tileSizeMeters
  > 0, capturedAt within [now - MaxAgeDays, now + future-skew]; uses an
  injectable TimeProvider so unit tests can drive a fixed clock.
- UavUploadValidationFilter: IEndpointFilter that reads the multipart
  `metadata` form field, deserializes it with the strict global
  JsonSerializerOptions (so UnmappedMemberHandling.Disallow +
  [JsonRequired] from AZ-795 are honored), runs the FluentValidation
  chain, and enforces the cross-field `items.Count == files.Count`
  envelope rule. FluentValidation errors are prefixed with `metadata.`
  so wire keys look like `errors["metadata.items[0].latitude"]`.

[JsonRequired] is added to every non-optional axis on
UavTileMetadata and UavTileBatchMetadataPayload; FlightId stays
nullable per AZ-503 anonymous-flight semantics.

Coverage: 13 unit tests + 16 integration tests + 1 curl probe script
exercise the happy path and every failure mode. All 9 ACs covered;
no regression in AZ-488 UavUploadTests payloads (traced against the
new rules).

Documentation: uav-tile-upload.md bumped v1.1.0 -> v1.2.0 with the
new validation rules section + 400-shape examples + changelog entry.
api_program.md updated to describe the three new validators + filter
+ the AddTransient<UavUploadValidationFilter>() DI registration.

Reports: batch_04_cycle8_report.md + reviews/batch_04_cycle8_review.md
record the PASS_WITH_WARNINGS verdict (2 Low DRY-in-tests findings:
FixedTimeProvider duplication crossed the cycle-2 "promote to shared"
threshold; PostBatch helper duplicated between two integration
suites). Both deferred to follow-up PBIs.

Task spec archived: _docs/02_tasks/todo/AZ-810... -> done/.
Jira: AZ-810 transitioned In Progress -> In Testing.

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

SatelliteProvider.Api/Program.cs

@@ -122,6 +122,11 @@ builder.Services.ConfigureHttpJsonOptions(options =>
 builder.Services.AddValidatorsFromAssemblyContaining<Program>();
 GlobalValidatorConfig.ApplyOnce();
 
+// AZ-810: explicit registration so `.AddEndpointFilter<UavUploadValidationFilter>()`
+// on the UAV upload endpoint resolves the filter with its `IValidator<…>` + JSON
+// options constructor deps. Transient so each request gets a fresh instance.
+builder.Services.AddTransient<UavUploadValidationFilter>();
+
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen(c =>
 {
@@ -231,6 +236,7 @@ app.MapPost("/api/satellite/tiles/inventory", GetTilesInventory)
 
 app.MapPost("/api/satellite/upload", UploadUavTileBatch)
     .RequireAuthorization(SatellitePermissions.UavUploadPolicy)
+    .AddEndpointFilter<UavUploadValidationFilter>()
     .Accepts<UavTileBatchUploadRequest>("multipart/form-data")
     .Produces<UavTileBatchUploadResponse>(StatusCodes.Status200OK)
     .ProducesProblem(StatusCodes.Status400BadRequest)