[FEATURE] 3D marker surface

[aelligp]

Whats the purpose of this PR?

• Bug fix
• New feature
• Documentation update
• Other, please explain

Describe it in more detail below:
This adds the "marker" surface to JP. The codes are based on the surf.cpp/surf.h file from LaMEM and were translated by Claude Opus 4.6. I have verified and tested it myself and think it's a good initial implementation we can build upon and discuss.

Checklist

• The PR title is descriptive and starts with the appropriate tag: [BUGFIX], [ADDITION], [DOC], etc.
• New tests (either assessing the correct behaviour of new internal functions or the correctness of a miniapps or benchmarks) were added, or old tests were updated
• Affected miniapps have also been updated
• The new feature was added in a way that does not break public API
• New documentation related to the new feature was added
• The new code follows the contributor guidelines, in particular the Runic Style

[codecov]

Codecov Report

❌ Patch coverage is 69.14191% with 187 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/MarkerSurface/areas.jl	66.32%	66 Missing ⚠️
src/MarkerSurface/Advection/advect_topo.jl	80.60%	32 Missing ⚠️
ext/JustPICAMDGPUExt.jl	0.00%	31 Missing ⚠️
ext/JustPICCUDAExt.jl	0.00%	31 Missing ⚠️
src/MarkerSurface/Advection/advection.jl	26.31%	14 Missing ⚠️
src/MarkerSurface/smoothing.jl	91.42%	6 Missing ⚠️
src/MarkerSurface/interp_velocity.jl	95.31%	3 Missing ⚠️
src/Interpolations/utils.jl	0.00%	2 Missing ⚠️
src/particles.jl	50.00%	2 Missing ⚠️

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