Sans spheres intensity fix

[Lomholy]

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Please describe what your PR is adding in terms of features or bugfixes:
The Sans_spheres comp was not matching the otherwise validated SANS_spheres2.comp in intensity, when simulated under similar circumstances. Likewise it was not matching an analytical calculation completely.

This PR adds a Sigma to the attenuation factor of the Sans_spheres component that brings it in line with the SANS_spheres2 component and the analytical calculation. This PR also adds a missing attenuation the SANS_spheres2 component, in the case that it only simulates 1 scattering event inside the sample.

Furthermore the Sans_spheres component was missing a conversion from deg to rad in its angular focusing option. This has been added with this PR.

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Declaration of use of AI-tools

• Please add a checkmark here if you used AI-tools during the work for this contribution
• Furter, please describe how / where and for what the tools were used:
  I used an AI to rewrite the header into a readme file.

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Development OS / boundary conditions

Please describe what OS you developed and tested your additions on, and if any special dependencies are required:
MacOS Tahoe 26.6.2

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PR Checklist for contributing to McStas/McXtrace

For a coherent and useful contribution to McStas/McXtrace, please fill in relevant parts of the checklist:

• My contribution includes patches to an existing component file

  • I have used the mcdoc utility and rendered a reasonable documentation page for the component (please attach as screenshot in comments!)
  • I have ensured that basic use of the component is OK (e.g. an instrument using it compiles?)
  • I have used the mctest utility to test one or more instruments making use of the component (please attach mcviewtest report as screenshot in comments)
  • I have used the mccode-clangformat tool to apply the standard McCode component indentation scheme
  • I have used the mcrun --c-lint "linter" and followed advice to remove most / all warnings that are raised

• My contribution includes a new instrument file

  • I have used the mcdoc utility and rendered a reasonable documentation page for the instrument (please attach as screenshot in comments!)
  • I have ensured that basic use of the instrument is OK (e.g. it compiles?)
  • ... and provided reasonable default parameters in that instrument that produce reasonable output
  • ... and maybe even added a %Example: line to describe expected behaviour
  • I have used the mcrun --c-lint "linter" and followed advice to remove most / all warnings that are raised
  • My new instrument is added within the examples hierarchy in a folder in the style of examples/ESS/New_stuff/New_stuff.instr
  • My new instrument has a new, unique filename, not clashing with existing example instruments

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[Lomholy]

Sans_spheres mcdoc:

SANS_spheres mcdoc:

Test_sans_spheres mcdoc: