feat(i18n): complete post-launch i18n phases 5-8

- Phase 5: Translate homepage-modern.html (~90 new locale keys, all
  hardcoded strings replaced with _() calls for dashboard mock,
  features, pricing tiers, testimonial sections)
- Phase 6: Translate homepage-minimal.html (17 new locale keys for
  fallback content, features, and CTA sections)
- Phase 7: Add multi-language page.title/content support with
  title_translations and content_translations JSON columns, Alembic
  migration cms_002, translated title/content resolution in templates,
  and seed script updates with tt() helper
- Phase 8: Complete lb.json audit — fill 6 missing keys (messages,
  confirmations), also backfill same keys in fr.json and de.json

All 4 locale files now have 340 keys with full parity.

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

app/modules/cms/models/content_page.py

@@ -118,6 +118,21 @@ class ContentPage(Base):
         comment="Structured homepage sections (hero, features, pricing, cta) with i18n",
     )
 
+    # Multi-language title and content (JSON dicts keyed by language code)
+    # e.g. {"en": "About Us", "fr": "À propos", "de": "Über uns", "lb": "Iwwer eis"}
+    title_translations = Column(
+        JSON,
+        nullable=True,
+        default=None,
+        comment="Language-keyed title dict for multi-language support",
+    )
+    content_translations = Column(
+        JSON,
+        nullable=True,
+        default=None,
+        comment="Language-keyed content dict for multi-language support",
+    )
+
     # SEO
     meta_description = Column(String(300), nullable=True)
     meta_keywords = Column(String(300), nullable=True)
@@ -195,6 +210,26 @@ class ContentPage(Base):
             return "store_default"
         return "store_override"
 
+    def get_translated_title(self, lang: str, default_lang: str = "fr") -> str:
+        """Get title in the given language, falling back to default_lang then self.title."""
+        if self.title_translations:
+            return (
+                self.title_translations.get(lang)
+                or self.title_translations.get(default_lang)
+                or self.title
+            )
+        return self.title
+
+    def get_translated_content(self, lang: str, default_lang: str = "fr") -> str:
+        """Get content in the given language, falling back to default_lang then self.content."""
+        if self.content_translations:
+            return (
+                self.content_translations.get(lang)
+                or self.content_translations.get(default_lang)
+                or self.content
+            )
+        return self.content
+
     def to_dict(self):
         """Convert to dictionary for API responses."""
         return {
@@ -206,7 +241,9 @@ class ContentPage(Base):
             "store_name": self.store.name if self.store else None,
             "slug": self.slug,
             "title": self.title,
+            "title_translations": self.title_translations,
             "content": self.content,
+            "content_translations": self.content_translations,
             "content_format": self.content_format,
             "template": self.template,
             "sections": self.sections,