Ephemeral theme arg

[grantmcdermott]

Closes #442

MWE

pkgload::load_all('~/Documents/Projects/tinyplot')
#> ℹ Loading tinyplot
plt(bill_dep ~ bill_len | species, data = penguins)

plt(bill_dep ~ bill_len | species, data = penguins, theme = 'clean')
plt_add(type = 'lm')

plt(bill_dep ~ bill_len | species, data = penguins)

^{Created on 2025-09-16 with reprex v2.1.1}

[zeileis]

Very nice, thanks for adding this.

I played around a bit how this interacts with tinyplot_add() or setting add = TRUE. I wasn't able to create weird or unexpected results, though, even when using different themes in the first and in the added plot. 👍

[grantmcdermott]

Super, thanks for testing @zeileis! I'll add a test when I get a sec and then merge (the failing altdoc action can be ignored).