Adds notes/example-images.org demonstrating how org-mode image links of
each kind pass through ox-hugo and land in content/:
Scenario 1 — External URL: linked image using #+ATTR_HTML + a local
thumbnail as the display image; ox-hugo emits a {{< figure >}} shortcode
with a link= attribute pointing to the remote URL.
Scenario 2 — Local file (same notes dir): [[file:quartz-logo.jpg]]
ox-hugo copies the file to static/ox-hugo/ and rewrites the src to
/ox-hugo/quartz-logo.jpg.
Scenario 3 — Absolute path outside notes dir: [[file:/abs/path/img.jpg]]
ox-hugo copies the file from outside the notes tree into static/ox-hugo/
and rewrites the src identically to scenario 2.
Also adds:
notes/quartz-logo.jpg — image asset for scenarios 1 & 2
notes-external/ — simulates an assets dir outside notes
static/ox-hugo/ added to .gitignore (populated at export time)
