Add highlight.js syntax highlighting to source viewer

- Install highlight.js via npm with 8 language definitions
- SourceViewer hook applies syntax highlighting on mount/update
- Atom One Dark theme for dark mode, Atom One Light for light mode
- Add hooks directory, package.json, and package-lock.json
- Add demo document and screenshots
- Add rodney-docker.md documentation
- Ignore .rodney/ chrome data directory

app/assets/package-lock.json

@@ -0,0 +1,25 @@
+{
+  "name": "assets",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "assets",
+      "version": "1.0.0",
+      "license": "ISC",
+      "dependencies": {
+        "highlight.js": "^11.11.1"
+      }
+    },
+    "node_modules/highlight.js": {
+      "version": "11.11.1",
+      "resolved": "https://registry.npmjs.org/highlight.js/-/highlight.js-11.11.1.tgz",
+      "integrity": "sha512-Xwwo44whKBVCYoliBQwaPvtd/2tYFkRQtXDWj1nackaV2JPXx3L0+Jvd8/qCJ2p+ML0/XVkJ2q+Mr+UVdpJK5w==",
+      "license": "BSD-3-Clause",
+      "engines": {
+        "node": ">=12.0.0"
+      }
+    }
+  }
+}