feat: i18n annotations — data-de/data-en + toggle for all 54 custom sites

Phase 2 of i18n rollout:
- All 54 static custom sites now have data-de/data-en attributes on
  visible text elements with English translations
- i18n.js script tag injected into all sites
- Language toggle button with machine-translation disclaimer added
  to every site's footer area
- Brand names / domain wordplay preserved unchanged in both languages
- 2 dynamic sites (dasbes.de, dumusst.com) skipped — no static HTML

sites/ichbinaufbali.de/index.html

@@ -100,8 +100,13 @@
     <div class="icon">🌴</div>
     <h1>Ich bin auf B<span class="accent">a</span>l<span class="accent">i</span>.</h1>
     <div class="divider"></div>
-    <p class="subtitle">Und du so?</p>
+    <p class="subtitle" data-de="Und du so?" data-en="And you?">Und du so?</p>
     <p class="footer">ichbinaufb<span style="color:var(--accent)">AI</span>.de</p>
   </div>
+  <div style="text-align:center;margin-top:16px;">
+    <button data-i18n-toggle title="Maschinell übersetzt / Machine-translated — German is the original." style="background:none;border:1px solid var(--text-muted,#444);color:var(--text-muted,#444);font-size:0.65rem;letter-spacing:0.1em;padding:4px 12px;border-radius:4px;cursor:pointer;">EN</button>
+    <br><small data-de="Maschinell übersetzt" data-en="Machine-translated" style="color:var(--text-muted,#444);font-size:0.6rem;opacity:0.5;">Maschinell übersetzt</small>
+  </div>
+  <script src="/shared/i18n.js"></script>
 </body>
 </html>