Fix SEO and accessibility issues in production build

- Change 'Hosted in the EU' from h3 to h2 for proper heading hierarchy
- Add FAQ structured data (JSON-LD) for rich search results
- Remove onclick attributes from copy buttons (event listeners in app.js)

These changes were previously applied to templates/pages/ but missing
from public/src/ which is used by the Docker build. All changes now
applied to correct source files and built.

public/partials/_modals.html

@@ -36,7 +36,7 @@
       </div>
       <div style="background:var(--bg);border:1px solid var(--accent);border-radius:8px;padding:14px;font-family:monospace;font-size:0.82rem;word-break:break-all;margin:16px 0;position:relative;">
         <span id="apiKeyText"></span>
-        <button onclick="copyKey()" id="copyBtn" aria-label="Copy API key" style="position:absolute;top:8px;right:8px;background:var(--accent);color:var(--bg);border:none;border-radius:4px;padding:4px 12px;cursor:pointer;font-size:0.8rem;">Copy</button>
+        <button id="copyBtn" aria-label="Copy API key" style="position:absolute;top:8px;right:8px;background:var(--accent);color:var(--bg);border:none;border-radius:4px;padding:4px 12px;cursor:pointer;font-size:0.8rem;">Copy</button>
       </div>
       <p style="margin-top:20px;color:var(--muted);font-size:0.9rem;">100 free PDFs/month • <a href="/docs">Read the docs →</a></p>
     </div>