seo(site): ship comparison, vs-termux, claude-code-android pages + internal links

3 long-tail pages targeting 'opencode vs chatgpt/copilot', 'vs termux',
'claude code on android'. Added to sitemap, footer nav, in-content links
from landing + guide + troubleshooting. All have canonical + install CTAs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs-site/guide/index.html

@@ -295,6 +295,7 @@ OPENCODE_SERVER_PASSWORD=yourpassword opencode serve --hostname 0.0.0.0 --port 4
       <a class="btn" href="https://github.com/dzianisv/opencode-mobile/releases/latest">Download APK</a>
       <a class="btn" href="../">Back to home</a>
     </div>
+    <p style="margin-top:20px">Also see: <a href="../vs-termux/">OpenCode Mobile vs Termux</a> — skip the terminal emulator setup and use the native Android UI instead. Or <a href="../claude-code-android/">run Claude Code on Android</a> — configure opencode with your Anthropic API key and use Claude Sonnet or Opus as your AI engine.</p>
   </div>
 </section>
 </main>