Makie inspector labels don’t work with rich text

[AUK1939]

Opening a github issue as suggested on Julia discourse here

Makie version: Makie v0.24.7
Platform/GPU: Windows + NVidia 4070.
Backend: GLMakie

Minimal repro

using GLMakie
GLMakie.activate!()

labels = ["Alpha", "Beta", "Gamma", "Delta"]
values = [12.5, 8.0, 15.0, 10.5]
colors = [:skyblue, :lightgreen, :gold, :orchid]

fig = Figure(resolution=(650, 400))
ax = Axis(fig[1, 1]; ylabel="Value", xlabel="Category", title="RichText inspector")

function custom_inspector_label_rich(self, idx, pos) 
        val = round(values[idx]; digits=2)
        return Makie.rich(
            Makie.rich("$(labels[idx])"; font=:bold, color=:purple),
            "\n",
            Makie.rich("Value: $val"; color=:green)
        )
end

function custom_inspector_label_plain(self, idx, pos) 
        val = round(values[idx]; digits=2)
        return "$(labels[idx])" * "\n" * "Value: $val"
end

barplot!(ax, values;
    color=colors,
    width=0.6,
    strokewidth=0,
    inspectable=true,
    inspector_label = custom_inspector_label_rich
)

ax.xticks = (1:length(values), labels)
DataInspector(fig)
fig

Expected: hovering shows a rich-text tooltip with bold label and colored value.
Observed: the inspector stack traces and fails because the RichText value cannot be converted to String (MethodError: cannot convert Makie.RichText to String), even though the documented inspector_label hook is used.