[AZ-284] Autodev baseline + testability refactor

Phase A baseline outputs from /autodev (Steps 1-5):
- Problem & solution docs (_docs/00_problem, _docs/01_solution)
- Codebase documentation (_docs/02_document) incl. architecture,
  module-layout, glossary, system-flows, baseline compliance scan
- Test specs (blackbox, performance, resilience, security, resource,
  traceability matrix)
- Test task decomposition (_docs/02_tasks/todo): AZ-285..AZ-290
- Testability refactor (_docs/04_refactoring/01-testability-refactoring):
  - TC-01 Move DownloadedTileInfoV2 + new ExistingTileInfo to Common.DTO
  - TC-02 Replace dead ISatelliteDownloader API with real signatures
  - TC-03 GoogleMapsDownloaderV2 implements ISatelliteDownloader
  - TC-04 TileService depends on ISatelliteDownloader (mockable)
  - TC-05 DI + endpoints use ISatelliteDownloader
- Test runner scripts (scripts/run-tests.sh, run-performance-tests.sh)
- Autodev state pointer (_docs/_autodev_state.md)

Prepares the codebase for AZ-285..AZ-290 unit/integration test work.

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

_docs/02_document/modules/dataaccess_tile_repository.md

@@ -0,0 +1,47 @@
+# Module: DataAccess/Repositories/TileRepository
+
+## Purpose
+Dapper-based repository for the `tiles` table. Handles CRUD operations and spatial queries for satellite tile records.
+
+## Public Interface
+
+### ITileRepository (interface)
+- `GetByIdAsync(Guid id) → Task<TileEntity?>`
+- `GetByTileCoordinatesAsync(int tileZoom, int tileX, int tileY) → Task<TileEntity?>`: finds tile by slippy map coordinates, returns latest version
+- `FindExistingTileAsync(double lat, double lon, double tileSizeMeters, int zoomLevel, int version) → Task<TileEntity?>`: fuzzy coordinate match (tolerance: 0.0001° lat/lon, 1m tile size)
+- `GetTilesByRegionAsync(double lat, double lon, double sizeMeters, int zoomLevel) → Task<IEnumerable<TileEntity>>`: spatial bounding box query with expanded range to cover tile edges
+- `InsertAsync(TileEntity tile) → Task<Guid>`: upsert — `ON CONFLICT (latitude, longitude, tile_zoom, tile_size_meters, version) DO UPDATE` file_path, tile_x, tile_y, updated_at
+- `UpdateAsync(TileEntity tile) → Task<int>`
+- `DeleteAsync(Guid id) → Task<int>`
+
+### TileRepository (implementation)
+Constructs a new `NpgsqlConnection` per method call (no connection pooling at the repository level; Npgsql pools connections internally).
+
+## Internal Logic
+- `GetTilesByRegionAsync` calculates a bounding box by expanding the requested region by 2 × tile size to ensure edge tiles are included. Uses meters-to-degrees approximation (111,000 m/degree latitude, adjusted for longitude).
+- `InsertAsync` uses an upsert pattern to handle duplicate tile downloads gracefully.
+- `GetByTileCoordinatesAsync` orders by `version DESC` and takes the latest.
+
+## Dependencies
+- NuGet: `Dapper`, `Npgsql`
+- `SatelliteProvider.DataAccess.Models.TileEntity`
+- `Microsoft.Extensions.Logging`
+
+## Consumers
+- `TileService` — all read/write operations
+- `Program.cs` (ServeTile, GetTileByLatLon handlers) — `GetByTileCoordinatesAsync`, `InsertAsync`
+
+## Data Models
+Operates on `TileEntity`.
+
+## Configuration
+Receives connection string via constructor.
+
+## External Integrations
+PostgreSQL — SQL queries via Dapper + Npgsql.
+
+## Security
+None.
+
+## Tests
+No dedicated repository tests.