interactive mermaid diagrams don't work

[ryepup]

Repro

• create a blank jekyll site configured with jekyll-spaceship

• make a markdown page like this:

  ---

  title: mermaid demo

    graph TD
      a[jekyll-spaceship]
      click a "https://github.com/jeffreytse/jekyll-spaceship" "view on github"

• run jekyll build

Expected behavior

Clicking the "jekyll-spaceship" node in the rendered graph navigates to https://github.com/jeffreytse/jekyll-spaceship

Actual behavior

Nothing

Analysis

mermaid-processor.rb gets the SVG from mermaid and renders it in an <img> tag. That tag does not support interactivity.

If we render it with an <object> tag, then the interactive elements in SVG work.

I think the relevant spot to change is here: https://github.com/jeffreytse/jekyll-spaceship/blob/7d86dcbe03aabbde70d4b30d5d5b483754672632/lib/jekyll-spaceship/processors/mermaid-processor.rb#L76

[ryepup]

looks like <object> won't work; I can click the link but it tries to navigate inside the <object> body, which isn't right

[ryepup]

fixed with e1a5bf7 and using mode: 'pre-fetch'