fix: use tee to write repo file instead of dnf config-manager

dnf config-manager cannot read from /dev/stdin as a repo file source.
Write the repo file directly with tee instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/Home.tsx

@@ -33,7 +33,7 @@ export function Home() {
 
               <h6 className="mt-4">2. Add the repository</h6>
               <CodeBlock language="bash">
-                {`sudo dnf config-manager addrepo --from-repofile=/dev/stdin <<'EOF'\n${REPO_FILE}\nEOF`}
+                {`sudo tee /etc/yum.repos.d/lair-cafe.repo > /dev/null <<'EOF'\n${REPO_FILE}\nEOF`}
               </CodeBlock>
 
               <h6 className="mt-4">3. Install a package</h6>