test(glossy): switch to typst-test, add tests

- move examples/readme.typ into a test (demo)
- add test for sorting (both ways)
- add test to generate theme gallery
- add theme gallery image to README

preview/glossy/0.2.1/tests/theme-gallery/test.typ

@@ -0,0 +1,54 @@
+#import "/lib.typ": *
+
+#let myGlossary = (
+  html: (
+    short: "HTML",
+    long: "Hypertext Markup Language",
+    description: "A standard language for creating web pages",
+  ),
+  css: (
+    short: "CSS",
+    long: "Cascading Style Sheets",
+    description: "A language used for describing the presentation of a document",
+  ),
+  tps: (
+    short: "TPS",
+    long: "test procedure specification",
+    description: "A document on how to run all the test procedures"
+  ),
+)
+
+#show: init-glossary.with(myGlossary, show-term: (body) => [#emph(body)])
+
+#text(size: 18pt, weight: "bold")[Theme Gallery]
+
+First, we refer to each term at least once so they'll actually show up in the
+glossaries. Our terms include: @html:cap, @css, and @tps.
+
+// TODO: ask Discord if there's a way to get a symbol (ie function) name as a
+// TODO: figure out if there's a way to get a symbol (ie function) name as a
+// string or content
+#let themes = (
+  ("theme-basic",   theme-basic),
+  ("theme-compact", theme-compact),
+)
+
+#for theme in themes {
+  block(
+    breakable: false,
+    spacing: 2em,
+    inset: 1em,
+    stroke: 1pt+gray,
+    glossary(title: raw(theme.first()), theme: theme.last())
+  )
+}
+
+// HACK: special case theme-twocol so we can restrict the height
+#block(
+  breakable: false,
+  spacing: 2em,
+  inset: 1em,
+  stroke: 1pt+gray,
+  height: 1.5in,
+  glossary(title: raw("theme-twocol"), theme: theme-twocol)
+)