feat: add show_in_legal category for bottom bar CMS pages

Add third placement category for content pages that appear in the
bottom bar alongside the copyright notice (Privacy Policy, Terms, etc.):

Model changes:
- Add show_in_legal boolean field to ContentPage model
- Add to to_dict() serialization

Service changes:
- Add legal_only filter to list_pages_for_vendor()

Platform changes:
- Fetch legal_pages in get_platform_context()
- Update base.html to render legal_pages dynamically
- Fallback to hardcoded links if no CMS pages configured

Migration:
- Add column with default=False
- Auto-set show_in_legal=True for privacy and terms pages

Categories:
- show_in_header: Top navigation
- show_in_footer: Quick Links column
- show_in_legal: Bottom bar with copyright (NEW)

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/routes/platform_pages.py

@@ -47,9 +47,10 @@ def get_platform_context(request: Request, db: Session) -> dict:
     # Add i18n globals (_, t, current_language, SUPPORTED_LANGUAGES, etc.)
     context.update(i18n_globals)
 
-    # Load CMS pages for header and footer navigation
+    # Load CMS pages for header, footer, and legal navigation
     header_pages = []
     footer_pages = []
+    legal_pages = []
     try:
         # Platform pages have vendor_id=None
         header_pages = content_page_service.list_pages_for_vendor(
@@ -58,14 +59,18 @@ def get_platform_context(request: Request, db: Session) -> dict:
         footer_pages = content_page_service.list_pages_for_vendor(
             db, vendor_id=None, footer_only=True, include_unpublished=False
         )
+        legal_pages = content_page_service.list_pages_for_vendor(
+            db, vendor_id=None, legal_only=True, include_unpublished=False
+        )
         logger.debug(
-            f"Loaded CMS pages: {len(header_pages)} header, {len(footer_pages)} footer"
+            f"Loaded CMS pages: {len(header_pages)} header, {len(footer_pages)} footer, {len(legal_pages)} legal"
         )
     except Exception as e:
         logger.error(f"Failed to load CMS navigation pages: {e}")
 
     context["header_pages"] = header_pages
     context["footer_pages"] = footer_pages
+    context["legal_pages"] = legal_pages
 
     return context