feat: AI/KI disclosure footer — shared/ai-disclosure.js + all 54 sites

Self-injecting script following impressum.js pattern:
- data-tone attribute: playful | serious | minimal | none
- Reads document.documentElement.lang for KI (de) vs AI (en)
- MutationObserver on lang attr for i18n toggle compat
- All tones link to msbls.de/ki
- Injected into all 54 custom sites with data-tone="playful"
- Template infra: base.html includes script, render.sh reads disclosure.tone
- disclosure.tone added to 3 example site.yaml files

Implements m/onepager#2

sites/knzlmgmt.de/index.html

@@ -57,6 +57,7 @@
     <p class="footer">knzlmgmt.de</p>
     <p class="footer" style="margin-top:12px;"><button data-i18n-toggle title="Maschinell übersetzt / Machine-translated — German is the original." style="background:none;border:1px solid var(--text-muted);color:var(--text-muted);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="font-size:0.6rem;opacity:0.5;">Maschinell übersetzt</small></p>
   </div>
+  <script src="/shared/ai-disclosure.js" data-tone="playful"></script>
   <script src="/shared/i18n.js"></script>
 </body>
 </html>