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

shared/ai-disclosure.js

@@ -0,0 +1,72 @@
+/**
+ * KI/AI disclosure for onepager sites.
+ *
+ * Include: <script src="/shared/ai-disclosure.js" data-tone="playful"></script>
+ *
+ * Configuration via data attributes on the script tag:
+ *   data-tone="playful"   — Lighthearted note with humor
+ *   data-tone="serious"   — Straightforward disclosure
+ *   data-tone="minimal"   — Single compact label
+ *   data-tone="none"      — No disclosure (script does nothing)
+ *
+ * Language is read from document.documentElement.lang:
+ *   "de" -> KI terminology, "en" -> AI terminology.
+ * All tones link to msbls.de/ki.
+ */
+(function () {
+  var script = document.currentScript;
+  var tone = (script && script.getAttribute('data-tone')) || 'minimal';
+
+  if (tone === 'none') return;
+
+  var lang = (document.documentElement.lang || 'de').slice(0, 2).toLowerCase();
+  var isEn = lang === 'en';
+
+  var texts = {
+    minimal: isEn ? 'AI-assisted' : 'KI-unterst\u00FCtzt',
+    serious: isEn
+      ? 'This site was created with AI assistance.'
+      : 'Diese Seite wurde mit Unterst\u00FCtzung von KI erstellt.',
+    playful: isEn
+      ? 'Made with AI (no AIs were harmed)'
+      : 'Mit KI gemacht (keine KI wurde verletzt)',
+  };
+
+  var text = texts[tone] || texts.minimal;
+
+  var el = document.createElement('div');
+  el.className = 'onepager-ai-disclosure';
+  el.innerHTML = '<a href="https://msbls.de/ki" target="_blank" rel="noopener">' + text + '</a>';
+
+  el.style.cssText = 'text-align:center;font-size:0.65rem;opacity:0.4;padding:6px 0;margin-top:2px;';
+  var a = el.querySelector('a');
+  if (a) {
+    a.style.color = 'inherit';
+    a.style.textDecoration = 'none';
+  }
+
+  // i18n: update text when language changes
+  var observer = new MutationObserver(function () {
+    var newLang = (document.documentElement.lang || 'de').slice(0, 2).toLowerCase();
+    var newIsEn = newLang === 'en';
+    var newTexts = {
+      minimal: newIsEn ? 'AI-assisted' : 'KI-unterst\u00FCtzt',
+      serious: newIsEn
+        ? 'This site was created with AI assistance.'
+        : 'Diese Seite wurde mit Unterst\u00FCtzung von KI erstellt.',
+      playful: newIsEn
+        ? 'Made with AI (no AIs were harmed)'
+        : 'Mit KI gemacht (keine KI wurde verletzt)',
+    };
+    var link = el.querySelector('a');
+    if (link) link.textContent = newTexts[tone] || newTexts.minimal;
+  });
+  observer.observe(document.documentElement, { attributes: true, attributeFilter: ['lang'] });
+
+  var footer = document.querySelector('footer .container, footer');
+  if (footer) {
+    footer.appendChild(el);
+  } else {
+    document.body.appendChild(el);
+  }
+})();