[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/components/01_common/description.md

@@ -0,0 +1,90 @@
+# Common (Foundation)
+
+## 1. High-Level Overview
+
+**Purpose**: Shared foundation layer containing configuration POCOs, data transfer objects, service interface contracts, and geographic computation utilities used by all other components.
+
+**Architectural Pattern**: Shared Kernel / Contracts Library
+
+**Upstream dependencies**: None (leaf)
+
+**Downstream consumers**: DataAccess, TileDownloader, RegionProcessing, RouteManagement, WebApi, Tests
+
+## 2. Internal Interfaces
+
+This component defines the service contracts that other components implement:
+
+### Interface: ITileService
+| Method | Input | Output | Async | Error Types |
+|--------|-------|--------|-------|-------------|
+| `DownloadAndStoreTilesAsync` | lat, lon, sizeMeters, zoomLevel, CancellationToken | `List<TileMetadata>` | Yes | Exception |
+| `GetTileAsync` | Guid id | `TileMetadata?` | Yes | Exception |
+| `GetTilesByRegionAsync` | lat, lon, sizeMeters, zoomLevel | `IEnumerable<TileMetadata>` | Yes | Exception |
+
+### Interface: IRegionService
+| Method | Input | Output | Async | Error Types |
+|--------|-------|--------|-------|-------------|
+| `RequestRegionAsync` | id, lat, lon, sizeMeters, zoomLevel, stitchTiles | `RegionStatus` | Yes | Exception |
+| `GetRegionStatusAsync` | Guid id | `RegionStatus?` | Yes | Exception |
+| `ProcessRegionAsync` | Guid id, CancellationToken | void | Yes | RateLimitException, HttpRequestException, TimeoutException |
+
+### Interface: IRouteService
+| Method | Input | Output | Async | Error Types |
+|--------|-------|--------|-------|-------------|
+| `CreateRouteAsync` | `CreateRouteRequest` | `RouteResponse` | Yes | ArgumentException |
+| `GetRouteAsync` | Guid id | `RouteResponse?` | Yes | Exception |
+
+### Interface: IRegionRequestQueue
+| Method | Input | Output | Async | Error Types |
+|--------|-------|--------|-------|-------------|
+| `EnqueueAsync` | `RegionRequest`, CancellationToken | void | Yes | OperationCanceledException |
+| `DequeueAsync` | CancellationToken | `RegionRequest?` | Yes | OperationCanceledException |
+
+### Static: GeoUtils
+| Method | Input | Output | Async | Error Types |
+|--------|-------|--------|-------|-------------|
+| `WorldToTilePos` | GeoPoint, zoom | (x, y) | No | - |
+| `TileToWorldPos` | x, y, zoom | GeoPoint | No | - |
+| `CalculateIntermediatePoints` | start, end, maxSpacing | `List<GeoPoint>` | No | - |
+| `CalculateDistance` | p1, p2 | double (meters) | No | - |
+| `GetBoundingBox` | center, radiusM | (minLat, maxLat, minLon, maxLon) | No | - |
+| `DirectionTo` (ext) | p1, p2 | Direction | No | - |
+| `GoDirection` (ext) | start, direction | GeoPoint | No | - |
+
+## 3. External API Specification
+
+N/A — internal-only component.
+
+## 4. Data Access Patterns
+
+N/A — no data access.
+
+## 5. Implementation Details
+
+**State Management**: Stateless (pure data types and static utilities)
+
+**Key Dependencies**: None (no NuGet packages)
+
+**Algorithmic Complexity**: GeoUtils uses Haversine formula (O(1) per calculation). `CalculateIntermediatePoints` is O(n) where n = ceil(distance / maxSpacing).
+
+## 6. Extensions and Helpers
+
+| Helper | Purpose | Used By |
+|--------|---------|---------|
+| GeoUtils | Coordinate conversions, distance/bearing math, point interpolation | TileDownloader, RegionProcessing, RouteManagement, WebApi |
+
+## 7. Caveats & Edge Cases
+
+- `GeoPoint` equality uses a tolerance of 0.00005° (~5.5m), which may cause false positives for closely-spaced tiles at high zoom levels
+- `DatabaseConfig` is defined but never wired via DI — connection string is read directly from `IConfiguration`
+- `ISatelliteDownloader` interface exists but is not implemented by `GoogleMapsDownloaderV2` (legacy artifact)
+
+## 8. Dependency Graph
+
+**Must be implemented after**: nothing
+**Can be implemented in parallel with**: DataAccess
+**Blocks**: TileDownloader, RegionProcessing, RouteManagement, WebApi
+
+## 9. Logging Strategy
+
+N/A — no logging in this component.