style: lighter inline code, black system bars for the installed app

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/lib/markdown.tsx

@@ -86,7 +86,7 @@ function renderInlineTokens(text: string, options?: InlineMarkdownOptions): Reac
       }
     } else if (token.startsWith('`') && token.endsWith('`')) {
       elements.push(
-        <code key={key} className="px-1.5 py-0.5 rounded bg-code text-main font-mono text-[0.9em] border border-border/50">
+        <code key={key} className="px-1.5 py-0.5 rounded bg-main/[0.12] text-main font-mono text-[0.9em]">
           {token.slice(1, -1)}
         </code>
       );