Clean up recipe kwargs

[Ickaser]

I've been bothered for a while by the workarounds for taking markers off when using the :samplemarkers recipe type, and when to use or not use the sampmarks kwarg in recipes on top of it. Still deciding what a reasonable API is.

[Ickaser]

This is a breaking change: will just need some release notes about the methods which got showline as a kwarg and the ones which got showmarks instead.

The sampmarks kwarg is still allowed and does its function, but will issue a depwarn. As such, this shouldn't be a breaking change.

[Copilot]

Pull request overview

This PR refactors plotting recipe keyword arguments to reduce confusion around :samplemarkers, primarily by deprecating sampmarks and introducing clearer showline / showmarks keywords, with accompanying documentation/example updates.

Changes:

• Updated the :samplemarkers recipe to better handle “line off” vs “markers off” scenarios by conditionally adding line/marker series.
• Deprecated sampmarks in multiple user recipes and mapped it to the new keywords via Base.depwarn.
• Updated docs/examples to use the new keyword arguments and adjusted some narrative text.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
src/recipes.jl	Refactors :samplemarkers internals; introduces showline/showmarks; deprecates sampmarks; updates recipe docs and examples.
docs/example/utilities.jl	Updates example plot call to new keyword usage.
docs/example/fitting_rf_mannitol.jl	Updates example plot call and adds explanatory comments for PD end detection.
docs/example/fitting_mannitol.jl	Switches PD end detection mode used in the example.
docs/example/all_recipes.jl	Updates recipe examples to use showline/showmarks instead of sampmarks.

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