[AZ-503] Tile identity → UUIDv5 + integer UPSERT (foundation)

Foundation half of original AZ-503 (split during /autodev step 10 batch 2
on user choice; deferred work moved to AZ-505 with a Blocks link).

Adds deterministic tile identity (UUIDv5 over (z, x, y, source, flight_id))
shared cross-repo with gps-denied-onboard via the pinned TileNamespace
5b8d0c2e-7f1a-4d3b-9c5e-1f3a8e7d2b6c, switches the tiles UPSERT key from
floats to integers with per-flight separation, plumbs FlightId through
UavTileMetadata + handler, and writes UAV evidence to per-flight
on-disk directories so two flights at the same (z, x, y) coexist.

- Common: pure-C# RFC 9562 Uuidv5 (no third-party dep) + FlightId DTO
  field; 10 Python-reference unit vectors verify byte parity.
- DataAccess: migration 014 adds flight_id (uuid NULL), location_hash
  (uuid NOT NULL, backfilled via session-scoped pg_temp.uuidv5),
  content_sha256 (bytea NULL), legacy_id (uuid NULL = preserves
  pre-AZ-503 random id one cycle); drops idx_tiles_unique_location_source
  (AZ-484) and adds idx_tiles_unique_identity keyed on
  (tile_zoom, tile_x, tile_y, tile_size_meters, source,
   COALESCE(flight_id, '00000000-...'::uuid)) + idx_tiles_location_hash.
- TileRepository: ColumnList + UPSERT updated; id never updated on
  conflict (preserves AC-2 idempotence). UpdateAsync extended.
- Services: TileService and UavTileUploadHandler compute deterministic
  Id + LocationHash + ContentSha256 before insert; UAV file path
  becomes ./tiles/uav/{flight_id or 'none'}/{z}/{x}/{y}.jpg.
- Tests: Uuidv5Tests (10 reference vectors), UavTileFilePathTests
  (per-flight + anonymous paths), UavTileUploadHandlerTests (AC-2,
  AC-3, AC-7, AC-11 unit-level), UavUploadTests (AC-3 + AC-4
  integration: multi-flight DB coexistence with shared location_hash
  + distinct file_path; float-different lat/lon collapse to 1 row),
  MigrationTests (column shape, idx_tiles_unique_identity supersedes
  AZ-484 index, deterministic backfill).
- IntegrationTests project references Common to reuse Uuidv5 in raw
  SQL seeds.
- AZ-488 MultiSourceCoexistence seed fixed to populate location_hash
  (otherwise migration 014's NOT NULL constraint fails).

ACs covered: AC-1, AC-2, AC-3, AC-4, AC-7, AC-8, AC-11.
ACs deferred to AZ-505: AC-5, AC-6, AC-9, AC-10, AC-12.

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

SatelliteProvider.Common/DTO/UavTileMetadata.cs

@@ -3,6 +3,12 @@ namespace SatelliteProvider.Common.DTO;
 // AZ-488 / `uav-tile-upload.md` v1.0.0 — per-tile metadata supplied with each
 // batch item. `CapturedAt` is normalized to UTC by the upload handler before
 // reaching the persistence layer.
+//
+// AZ-503: `FlightId` is optional. When provided, two UAVs uploading the same
+// (z, x, y) cell from different flights coexist as distinct DB rows and write
+// to per-flight on-disk paths (./tiles/uav/{flight_id}/{z}/{x}/{y}.jpg). When
+// absent, the row is treated as flight-anonymous and the UPSERT collapses to
+// the AZ-484 "single row per (cell, source)" semantics via COALESCE-to-zero.
 public record UavTileMetadata
 {
     public double Latitude { get; init; }
@@ -10,6 +16,7 @@ public record UavTileMetadata
     public int TileZoom { get; init; }
     public double TileSizeMeters { get; init; }
     public DateTime CapturedAt { get; init; }
+    public Guid? FlightId { get; init; }
 }
 
 public record UavTileBatchMetadataPayload