You wrote:
Please copy the file libEiffelSoftware.Library.Base.dll  under the bin\Debug\net8.0 subfolder  (in W_code)
Or, avoid using precompile library for now on calculator.ecf

File libEiffelSoftware.Library.Base.dll does not exist in bin\Debug\net8.0 subfolder (in W_code).
The closest file that does exist is EiffelSoftware.Library.Base.dll or libcalculator.dll

ACTION TAKEN
==============
Remove from counter.ecf: <precompile name="precompile" location="$ISE_PRECOMP\base-safe.ecf"/>

RESULT
=======
Code runs in Visual Studio.  SUCCESS

REMAINING DEFECT 1
=================
Can't run calculator within Visual Studio

Target Selection: classic, executed within Eiffel Studio
Let's add 2 1 +, then q for quit
Help details
Enter a number, followed by <return>: 1 ENTER
Accumulator = 1
Next operation: a ENTER
Enter a number, followed by <return>: 2 ENTER
Accumulator = 2
Next operation: + ENTER
Accumulator = 3
Next operation: q ENTER
Press Return to finish the execution...  ENTER

Target Selection: dotnet, executed within Visual Studio
Let's add 2 1 +, then q for quit
Help details
Enter a number, followed by <return>: 1 ENTER
Accumulator = 1
Next operation: a ENTER
ENTER    (only in dotnet version)
Enter a number, followed by <return>: 2 ENTER
Accumulator = 2
Next operation: + ENTER
ENTER    (only in dotnet version)
Accumulator = 3
Next operation: q ENTER
ENTER    (only in dotnet version)
Press Return to finish the execution...  ENTER

In Visual Studio, when entering a number, it works exactly the same as Eiffel Studio classic.
In Visual Studio, when entering a or + or q, it requires an additional ENTER key to be typed in.
------------------------------------------------------

REMAINING DEFECT 2
=================
You wrote: 
Issue: Can't run calculator in Eiffel Studio in dotnet target.

To fix the EiffelStudio debugging, can you try to add %ISE_EIFFEL%\studio\spec\%ISE_PLATFORM%\bin\netcore to your PATH ?
set PATH=%ISE_EIFFEL%\studio\spec\%ISE_PLATFORM%\bin\netcore;%PATH%

ACTION TAKEN
==============
In Windows 11, System Properties.  Click “Environment Variables”.
Under bottom “System variables” pane, select Path, then click “Edit...”
Click New
Paste in:  %ISE_EIFFEL%\studio\spec\%ISE_PLATFORM%\bin\netcore    (This fails because ISE_EIFFEL and ISE_PLATFORM not in Environment Variables)
Actually Pasted in: C:\Program Files\Eiffel Software\EiffelStudio 24.05 Standard\studio\spec\win64\bin\netcore
Click OK.

Remove EIFGENs directory.
In Eiffel Studio, Run with F5, Success.

When debugging on PLUS.operation, and F11 into LINKED_STACK, Feature call on void target.
But when run with F5, it works.

========================
SUMMARY
========================
Successes:
1. Remove from counter.ecf: <precompile name="precompile" location="$ISE_PRECOMP\base-safe.ecf"/>
    This enables Visual Studio to run calculator

Failures:
1. io behaves differently in classic vs dotnet modes for reading non numbers such as + or q.
2. Environment variables not set when installing Eiffel Studio 24.05.
    Needed to add raw path
3. In Eiffel Studio, with dotnet mode, LINKED_STACK complains of Feature call on void target, but runs fine with F5 (run).

(Would you like these to be separate support tickets?)