Add script for writing anki structured content css (#1706)

* Add script for writing anki structured content css

* Add docs in npm-scripts.md

* Note where anki structured content rules come from

* Fix formatting inconsistency

docs/development/npm-scripts.md

@@ -3,6 +3,14 @@
 This file documents the scripts available in the [package.json](../../package.json) file.
 Scripts can be executed by running `npm run <name>`.
 
+- `anki:css-json:write`
+
+  Writes Anki structured content styling json for use when sending stuctured content dictionaries to Anki.
+
+  CSS rules are taken from `ext/css/structured-content.css` and converted into json.
+
+  CSS rule overrides and exclusions can be set in `dev/data/structured-content-overrides.css`.
+
 - `bench`
   Runs performance benchmarks.
 

package.json

@@ -10,6 +10,7 @@
     },
     "type": "module",
     "scripts": {
+        "anki:css-json:write": "node ./dev/bin/generate-css-json.js --dryRun --all",
         "bench": "vitest bench",
         "build": "node ./dev/bin/build.js",
         "build:libs": "node ./dev/bin/build-libs.js",