fix(vitepress): use one-dark-pro for code blocks in both themes

Code blocks render on a dark navy background (--vp-code-block-bg) in both
light and dark mode, but VitePress's default Shiki themes (github-light/
github-dark) have muted tokens tuned for light backgrounds, leaving
identifiers nearly invisible. Pin one-dark-pro for both modes so syntax
stays legible on the navy.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ConorOkus

docs/.vitepress/config.mts

@@ -141,6 +141,14 @@ export default defineConfig({
 
   markdown: {
     lineNumbers: false,
+    // Code blocks use a dark navy background in BOTH light and dark mode
+    // (--vp-code-block-bg is dark in :root and .dark alike), so both Shiki
+    // themes must be dark-on-navy. github-light/github-dark have muted tokens
+    // that disappear on the navy; one-dark-pro stays high-contrast and legible.
+    theme: {
+      light: 'one-dark-pro',
+      dark: 'one-dark-pro',
+    },
   },
 
   themeConfig: {