fix(i18n): resolve footer translation keys showing on non-homepage pages

SUMMARY:
Fixed critical bug where footer displayed translation keys (e.g.,
"footer.about_heading") instead of actual text on all pages except homepage.

ROOT CAUSE:
i18n-simple.js only loaded page-specific JSON files (e.g., privacy.json).
Footer translations were in homepage.json, so other pages couldn't access them.

SOLUTION:

1. Created common.json for Shared Translations:
   - Created locales/en/common.json (footer translations)
   - Created locales/de/common.json (footer translations)
   - Created locales/fr/common.json (footer translations)

2. Updated i18n-simple.js to Load Both:
   - Always loads common.json (footer, shared UI elements)
   - Loads page-specific JSON (privacy.json, about.json, etc.)
   - Merges both (page-specific takes precedence)

IMPACT:
✓ Footer now displays correctly in all 3 languages on ALL pages
✓ Privacy page: Footer translates properly (en/de/fr)
✓ All pages: Footer translations work regardless of page-specific JSON
✓ Scalable: Easy to add more shared translations to common.json

TESTING:
- Verified locally on privacy.html (footer displays "Tractatus Framework")
- All 3 languages load correctly from common.json
- Page-specific translations still work (privacy content translates)

🤖 Generated with Claude Code (https://claude.com/claude-code)

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

public/js/i18n-simple.js

@@ -74,13 +74,29 @@ const I18n = {
 
   async loadTranslations(lang) {
     try {
+      // Always load common translations (footer, navbar, etc.)
+      const commonResponse = await fetch(`/locales/${lang}/common.json`);
+      let commonTranslations = {};
+      if (commonResponse.ok) {
+        commonTranslations = await commonResponse.json();
+      }
+
+      // Load page-specific translations
       const pageName = this.detectPageName();
-      const response = await fetch(`/locales/${lang}/${pageName}.json`);
-      if (!response.ok) {
+      const pageResponse = await fetch(`/locales/${lang}/${pageName}.json`);
+      let pageTranslations = {};
+      if (pageResponse.ok) {
+        pageTranslations = await pageResponse.json();
+      } else if (pageName !== 'homepage') {
+        // If page-specific translations don't exist, that's okay for some pages
+        console.warn(`[i18n] No translations found for ${lang}/${pageName}, using common only`);
+      } else {
         throw new Error(`Failed to load translations for ${lang}/${pageName}`);
       }
-      this.translations = await response.json();
-      console.log(`[i18n] Loaded translations for page: ${pageName}`);
+
+      // Merge common and page-specific translations (page-specific takes precedence)
+      this.translations = { ...commonTranslations, ...pageTranslations };
+      console.log(`[i18n] Loaded translations: common + ${pageName}`);
     } catch (error) {
       console.error(`[i18n] Error loading translations:`, error);
       // Fallback to English if loading fails

public/locales/de/common.json

@@ -0,0 +1,31 @@
+{
+  "footer": {
+    "about_heading": "Tractatus Framework",
+    "about_text": "Architektonische Beschränkungen für KI-Sicherheit, die menschliche Entscheidungsfreiheit durch strukturelle, nicht aspirationale, Garantien wahren.",
+    "documentation_heading": "Dokumentation",
+    "documentation_links": {
+      "framework_docs": "Framework-Dokumentation",
+      "about": "Über uns",
+      "core_values": "Grundwerte",
+      "interactive_demo": "Interaktive Demo"
+    },
+    "support_heading": "Unterstützung",
+    "support_links": {
+      "koha": "Unterstützung (Koha)",
+      "transparency": "Transparenz",
+      "media_inquiries": "Medienanfragen",
+      "submit_case": "Fallstudie einreichen"
+    },
+    "legal_heading": "Rechtliches",
+    "legal_links": {
+      "privacy": "Datenschutzerklärung",
+      "contact": "Kontakt",
+      "github": "GitHub"
+    },
+    "te_tiriti_label": "Te Tiriti o Waitangi:",
+    "te_tiriti_text": "Wir erkennen Te Tiriti o Waitangi und unser Bekenntnis zu Partnerschaft, Schutz und Teilhabe an. Dieses Projekt respektiert die Māori-Datensouveränität (rangatiratanga) und kollektive Vormundschaft (kaitiakitanga).",
+    "copyright": "John G Stroh. Lizenziert unter",
+    "license": "Apache 2.0",
+    "location": "Hergestellt in Aotearoa Neuseeland 🇳🇿"
+  }
+}

public/locales/en/common.json

@@ -0,0 +1,31 @@
+{
+  "footer": {
+    "about_heading": "Tractatus Framework",
+    "about_text": "Architectural constraints for AI safety that preserve human agency through structural, not aspirational, guarantees.",
+    "documentation_heading": "Documentation",
+    "documentation_links": {
+      "framework_docs": "Framework Docs",
+      "about": "About",
+      "core_values": "Core Values",
+      "interactive_demo": "Interactive Demo"
+    },
+    "support_heading": "Support",
+    "support_links": {
+      "koha": "Support (Koha)",
+      "transparency": "Transparency",
+      "media_inquiries": "Media Inquiries",
+      "submit_case": "Submit Case Study"
+    },
+    "legal_heading": "Legal",
+    "legal_links": {
+      "privacy": "Privacy Policy",
+      "contact": "Contact Us",
+      "github": "GitHub"
+    },
+    "te_tiriti_label": "Te Tiriti o Waitangi:",
+    "te_tiriti_text": "We acknowledge Te Tiriti o Waitangi and our commitment to partnership, protection, and participation. This project respects Māori data sovereignty (rangatiratanga) and collective guardianship (kaitiakitanga).",
+    "copyright": "John G Stroh. Licensed under",
+    "license": "Apache 2.0",
+    "location": "Made in Aotearoa New Zealand 🇳🇿"
+  }
+}

public/locales/fr/common.json

@@ -0,0 +1,31 @@
+{
+  "footer": {
+    "about_heading": "Tractatus Framework",
+    "about_text": "Contraintes architecturales pour la sécurité de l'IA qui préservent l'autonomie humaine par des garanties structurelles, et non aspirationnelles.",
+    "documentation_heading": "Documentation",
+    "documentation_links": {
+      "framework_docs": "Documentation du Framework",
+      "about": "À propos",
+      "core_values": "Valeurs fondamentales",
+      "interactive_demo": "Démo interactive"
+    },
+    "support_heading": "Support",
+    "support_links": {
+      "koha": "Support (Koha)",
+      "transparency": "Transparence",
+      "media_inquiries": "Demandes des médias",
+      "submit_case": "Soumettre une étude de cas"
+    },
+    "legal_heading": "Légal",
+    "legal_links": {
+      "privacy": "Politique de confidentialité",
+      "contact": "Nous contacter",
+      "github": "GitHub"
+    },
+    "te_tiriti_label": "Te Tiriti o Waitangi :",
+    "te_tiriti_text": "Nous reconnaissons Te Tiriti o Waitangi et notre engagement envers le partenariat, la protection et la participation. Ce projet respecte la souveraineté des données māori (rangatiratanga) et la tutelle collective (kaitiakitanga).",
+    "copyright": "John G Stroh. Sous licence",
+    "license": "Apache 2.0",
+    "location": "Fabriqué en Aotearoa Nouvelle-Zélande 🇳🇿"
+  }
+}