[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_migrator.md

@@ -0,0 +1,49 @@
+# Module: DataAccess/DatabaseMigrator
+
+## Purpose
+Runs DbUp-based SQL migrations against PostgreSQL on application startup. Ensures the database schema is up to date before the API begins serving requests.
+
+## Public Interface
+
+### DatabaseMigrator
+- Constructor: `DatabaseMigrator(string connectionString, ILogger<DatabaseMigrator>? logger)`
+- `RunMigrations() → bool`: creates the database if missing (`EnsureDatabase.For.PostgresqlDatabase`), then runs all embedded SQL scripts matching `.Migrations.` from the DataAccess assembly. Returns `true` on success.
+
+## Internal Logic
+- Uses `DbUp.DeployChanges` fluent API targeting PostgreSQL
+- Scripts are embedded resources filtered by path containing `.Migrations.`
+- Logs to console via DbUp's built-in `LogToConsole()`
+- On failure, logs the error and returns `false`
+
+## Dependencies
+- NuGet: `dbup-postgresql` (6.0.3)
+- `Microsoft.Extensions.Logging`
+- Embedded SQL resources from `SatelliteProvider.DataAccess/Migrations/`
+
+## Consumers
+- `Program.cs` — instantiated directly (not via DI) and called during startup. If migration fails, the application throws and does not start.
+
+## Migrations (11 scripts)
+1. `001_CreateTilesTable.sql`
+2. `002_CreateRegionsTable.sql`
+3. `003_CreateIndexes.sql`
+4. `004_AddVersionColumn.sql`
+5. `005_CreateRoutesTables.sql`
+6. `006_AddStitchTilesToRegions.sql`
+7. `007_AddRouteMapFields.sql`
+8. `008_AddGeofenceFlagToRouteRegions.sql`
+9. `009_AddGeofencePolygonIndex.sql`
+10. `010_AddTilesZipToRoutes.sql`
+11. `011_AddTileCoordinates.sql`
+
+## Configuration
+Receives connection string directly as constructor parameter.
+
+## External Integrations
+PostgreSQL — DDL operations via DbUp.
+
+## Security
+None directly, but controls schema evolution.
+
+## Tests
+No dedicated tests.