fix: resolve JS-005, JS-006, SVC-006 architecture violations

- JS-005: Add initialization guards to email-templates.js (admin/vendor)
- JS-006: Add try/catch error handling to content-pages.js init
- SVC-006: Move db.commit() from services to endpoints for proper
  transaction control in email_template_service and vendor_team_service

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

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

app/api/v1/vendor/team.py

@@ -385,6 +385,7 @@ def list_roles(
     vendor = request.state.vendor
 
     roles = vendor_team_service.get_vendor_roles(db=db, vendor_id=vendor.id)
+    db.commit()  # Commit in case default roles were created
 
     return RoleListResponse(roles=roles, total=len(roles))