Complete SC5/SV5 round-trip serialization and editor support in ObjectEditor

[Copilot]

This updates the partial SC5/SV5 implementation to support reliable load/save round-tripping for OpenLoco map files, including packed object chunks and tile-element data. It also fills key S5 structure gaps and wires map-file editing paths needed by the editor UI.

• S5 binary model + serializer parity

  • Completed SCV5 write-path support for packed objects (S5Header + ObjectHeader + encoded payload).
  • Preserved packed-object chunk encoding/bytes on read so unchanged files can round-trip byte-identically.
  • Added tile-element serialization (TileElement.Write) and switched save logic to emit edited tile elements when available.
  • Corrected non-scenario game-state writing to emit the correct save struct variants (GameStateSave1/GameStateSave2).
  • Removed read-time state mutation that altered fix flags and broke binary stability.

• S5 structure correctness fixes

  • Fixed ScenarioOptions.LandDistributionPatterns to the correct array shape.
  • Corrected scenario Orders sizing to kMaxOrders.
  • Made S5Header serializable as a nested loco struct to support chunk-based object serialization paths.

• Editor behavior

  • Enabled SC5/SV5 save/save-as flow in the SCV5 view model.
  • Updated tile-element rendering/edit surface to expose subtype/sub-structure fields for in-editor modifications.

• Regression coverage

  • Added SC5 and SV5 round-trip tests that assert load -> save yields byte-identical output.

// Packed object write format now mirrors OpenLoco S5 layout.
foreach (var packedObject in PackedObjects)
{
    bytes.AddRange(packedObject.Header.Write().ToArray());
    bytes.AddRange(
        packedObject.RawChunk
        ?? SawyerStreamWriter.WriteChunkCore(packedObject.Data, packedObject.Encoding));
}