Fix of issue: Address dotnet issues identified by Cursor #182

[mortensp]

I have made the following fixes:

• the calc_par are now exported through a dds_calc_table wrapper function in dds_api.cpp. This ensures proper C linkage and avoids name‑mangling issues. The two other calc_... exports are also prefixed dds_
• calc_par_from_table does not have a modern SolverContext‑based variant, which is why it is not included in the .NET wrapper for DDS. So no change here.
• One FreeMemory() call changed to ctx.ResetForSolve();
• Broken XML doc fixed
• ThrowIfError are marked [Conditional("DEBUG")] so it isn't called in release compiles.
• CalcDdTable are now named correctly in ThowIfError call
• Spurious using directives removed

Closes #182
Closes #184

[Copilot]

Pull request overview

This PR addresses .NET interop and wrapper issues by standardizing exported native entry points (avoiding C++ name mangling), updating P/Invoke declarations to match, and cleaning up .NET XML docs and debug-only error throwing behavior.

Changes:

• Rename/standardize v3 native exports to dds_* names and add a C-linkage wrapper export for calc_par.
• Update .NET P/Invoke and managed wrappers to call the new native entry points; make ThrowIfError debug-only via [Conditional("DEBUG")].
• Fix XML docs and remove spurious/unused using directives in .NET projects.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
library/src/dds_api.cpp	Adds/renames exported wrapper functions (dds_calc_dd_table*, dds_calc_par) for stable interop symbols.
library/src/api/dds_api.hpp	Updates exported function declarations to dds_* names and adds dds_calc_par.
library/src/api/calc_par.hpp	Removes an inconsistent DLLEXPORT on the C++ overload declaration.
dotnet/DDS_Core/Native/DdsNative.cs	Updates DllImport declarations to call the new dds_* native exports; removes unused usings.
dotnet/DDS_Core/Helpers/SolverContextHandle.cs	Cleans unused usings; keeps SafeHandle-based lifetime management.
dotnet/DDS_Core/DDS.cs	Fixes XML doc issues, makes ThrowIfError debug-only, and adjusts parameter ordering in managed APIs.
dotnet/DDS_Core/DataModel/SolverContext.cs	Updates to new dds_* P/Invoke names and makes ThrowIfError debug-only.
dotnet/DDS_Core_Demo/Program.cs	Updates demo usage and adds a v3 CalcPar sample invocation.