[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/deployment/environment_strategy.md

@@ -0,0 +1,32 @@
+# Environment Strategy
+
+## Environments
+
+| Environment | Purpose | Configuration Source |
+|-------------|---------|---------------------|
+| Development | Local development via docker-compose | appsettings.Development.json + docker-compose env |
+| Production | Deployed container | Environment variables |
+
+## Configuration Hierarchy
+
+1. `appsettings.json` — base defaults
+2. `appsettings.{Environment}.json` — environment overrides
+3. Environment variables — final override (production secrets)
+
+## Key Differences
+
+| Concern | Development | Production |
+|---------|-------------|------------|
+| Database host | localhost / postgres (container) | Environment variable |
+| Google Maps key | appsettings.Development.json | `MapConfig__ApiKey` env var |
+| Logging | Console + File | File only |
+| Swagger UI | Enabled | Enabled (no auth gate currently) |
+| Ports | 18980 (mapped from 8080) | 8080 |
+
+## Observability
+
+- **Logging**: Serilog writing to `./logs/` directory (file sink)
+- **Log format**: Structured (Serilog default)
+- **Metrics**: None currently implemented
+- **Health checks**: PostgreSQL readiness via `pg_isready`
+- **Tracing**: None currently implemented