Added TMatrix<T> and TObjectMatrix<T> to the Delphi runtime for two-dimensional scalar and object arrays.

Features

• Renamed the historical Pkg.* units to the product-oriented
  JsonToDelphi.* namespace. The Pkg prefix originated from the initials of
  Petar Georgiev, who created the original project. Since the codebase has been
  substantially rewritten and expanded, its unit names now describe the
  product and their architectural role instead of an individual developer.
• Renamed the former Lib directory to Runtime because these units are
  dependencies of the generated Delphi code. Existing projects must update
  their unit references, for example from Pkg.Json.DTO to
  JsonToDelphi.Runtime.DTO.
• Added centralized type unification in
  JsonToDelphi.Generator.Core.TypeUnification. The model builder now handles
  numeric promotion, nullability, nested arrays and structural object merging,
  while validation remains responsible for JSON syntax and source locations.
• Added TMatrix<T> and TObjectMatrix<T> to the Delphi runtime for
  two-dimensional scalar and object arrays. Both types own their row lists,
  while TObjectMatrix<T> also owns the objects contained in each row.
• Added C# matrix generation through a self-contained Matrix<T> type derived
  from List<List<T>>. The type works directly with System.Text.Json without
  requiring a custom converter.
• Added type-unification and matrix demo files covering numeric promotion,
  nullable values, structural object merging, scalar matrices, object
  matrices, empty rows and jagged matrices.
• Simplified the generated demo project's JSON tree view from six legacy units
  to one shared VCL and FMX implementation while preserving the original JSON
  visualization features.

Fixes

• Pasting JSON into the input editor no longer causes the application to become
  unresponsive due to recursive syntax highlighting.
• Fixed memory leaks in generated two-dimensional object arrays. Generated
  Delphi code now uses TObjectMatrix<T> so both row lists and their objects
  have explicit ownership.
• Added explicit Delphi JSON mapping for object matrices because Delphi's REST
  serializer cannot reliably deserialize TArray<TArray<TObject>> directly.
• Fixed C# string properties being emitted as object instead of string.
• Updated the demo-project template to include all required runtime units.
• Updated the end-to-end project unit search paths for the reorganized
  generator library.