fix: Suppress diagram translation warning on initial load, add home-ai locale stubs

- interactive-diagram.js: Only warn about missing translations when i18n
  has already initialized (not during initial race before i18n completes)
- Add empty home-ai.json locale files (en/de/fr) to prevent console
  warning on /home-ai.html page

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

public/js/components/interactive-diagram.js

@@ -21,7 +21,10 @@ class InteractiveDiagram {
     // If no translations available, use English fallback
     const hasTranslations = diagram && Object.keys(diagram).length > 0;
     if (!hasTranslations) {
-      console.warn('[InteractiveDiagram] No translations loaded, using English fallback');
+      // Only warn if i18n has already initialized (otherwise this is expected on first load)
+      if (window.i18nTranslations && Object.keys(window.i18nTranslations).length > 0) {
+        console.warn('[InteractiveDiagram] No diagram translations in loaded locale, using English fallback');
+      }
       this.loadFallbackData();
       return;
     }

public/locales/de/home-ai.json

@@ -0,0 +1,2 @@
+{
+}

public/locales/en/home-ai.json

@@ -0,0 +1,2 @@
+{
+}

public/locales/fr/home-ai.json

@@ -0,0 +1,2 @@
+{
+}