Standardize documentation plotting setup and prefer SVG output

[ocots]

Problem

The CTBase documentation build loads both Plots.jl and CairoMakie, but the plotting setup is not centralized in docs/make.jl. The current page-level setup disables PNG only for Plots.Plot, while CairoMakie is not explicitly configured to use SVG output.

With DocumenterVitepress, plot objects can advertise both image/png and image/svg+xml; PNG has the higher MIME priority and is selected unless PNG is disabled. This makes the generated documentation heavier and inconsistent with the desired vector output.

Proposed change

Update docs/make.jl so the global plotting setup:

• uses using Plots and import CairoMakie;
• activates CairoMakie with CairoMakie.activate!(; type="svg");
• disables image/png for Plots.Plot;
• disables image/png for CairoMakie.Makie.Figure.

Then remove redundant page-local MIME overrides and ensure all current and future @example blocks use SVG consistently.

Verification

julia --project=. docs/make.jl

The build should complete successfully and generate SVG assets without PNG plot assets.