[AZ-373] Refactor C20: drop MapsVersion from new writes (option a)

- Stop writing "downloaded_YYYY-MM-DD" into tiles.maps_version: new rows
  bind @MapsVersion to NULL via TileService.BuildTileEntity.
- Retain the tiles.maps_version column (coderule.mdc forbids unprompted
  column drops); pre-existing rows keep their values for forensics.
- Remove MapsVersion property from DownloadTileResponse (API wire shape)
  and TileMetadata (internal DTO); OpenAPI schema regenerates from the
  DTO via Swashbuckle.
- Add 3 AC tests in TileServiceTests covering the captured-entity write
  (AC-1) and the DTO/wire-shape removal (AC-2).
- Update integration-test local DTO + console output; refresh docs in
  common_dtos.md, services_tile_service.md, data_model.md.
- Archive AZ-373 task file: todo/ -> done/.

174 unit + 5 smoke pass.

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

_docs/02_tasks/done/AZ-373_refactor_clarify_mapsversion.md

@@ -0,0 +1,61 @@
+# Refactor: clarify or drop MapsVersion field
+
+**Task**: AZ-373_refactor_clarify_mapsversion
+**Name**: Decide MapsVersion semantics post-C06
+**Description**: Either drop `MapsVersion` from new tile rows (option a) or document it as a free-form provider-tag and keep it for forensics (option b). Decide alongside C06.
+**Complexity**: 2 points
+**Dependencies**: AZ-357 (C06)
+**Component**: Services.TileDownloader + DataAccess + Common
+**Tracker**: AZ-373
+**Epic**: AZ-350
+
+## Problem
+
+`SatelliteProvider.Services.TileDownloader/TileService.cs:154` writes `MapsVersion = $"downloaded_{now:yyyy-MM-dd}"` — the field name says "version" but the value is a creation-date label. The actual cache-key version is the `Version` integer (currently the year). C06 removes `Version` from the cache-key logic; `MapsVersion` is now doubly confusing.
+
+## Outcome
+
+- `MapsVersion` semantics are explicit (either removed from new writes or documented).
+- `tiles.maps_version` DB column is preserved (per `coderule.mdc` — no column drops without explicit confirmation).
+- 37 unit + 5 smoke tests stay green.
+
+## Scope
+
+### Included
+- Decide between (a) drop from new writes and stop emitting it in `DownloadTileResponse`, or (b) keep as a forensic free-form provider-tag with documentation in `TileMetadata.cs` and the OpenAPI spec.
+- Implement the chosen option.
+- Update `_docs/02_document/components/<owner>.md` to reflect the decision.
+
+### Excluded
+- Dropping the `tiles.maps_version` column (deferred per `coderule.mdc`).
+- Renaming the column.
+
+## Acceptance Criteria
+
+**AC-1: Semantics are explicit**
+Given the post-refactor source and docs
+When inspected
+Then `MapsVersion` is either no longer written by new code (option a) or documented as a free-form provider-tag (option b).
+
+**AC-2: HTTP shape decision recorded**
+Given the chosen option
+When `DownloadTileResponse` is inspected
+Then either the field is removed (option a) with the OpenAPI spec updated, or the field stays with documentation (option b).
+
+**AC-3: Tests stay green**
+Given the post-refactor build
+When `scripts/run-tests.sh --smoke` runs
+Then all 37 unit + 5 smoke scenarios pass.
+
+## Constraints
+
+- DB column kept either way.
+- No rename.
+
+## Risks & Mitigation
+
+**Risk 1: option choice needs implementation discretion**
+- *Risk*: this task documents both options; the implementer must pick one.
+- *Mitigation*: default to option (a) — drop from writes, keep column; this is the simpler path. If a downstream consumer relies on the field, fall back to option (b).
+
+Full change entry: `_docs/04_refactoring/03-code-quality-refactoring/list-of-changes.md` (C20).