Improved owner assignment, note handling, and stability

• More reliable agent→owner mapping
  • Sanitize and reuse agent_email, consistently track owner_id
• Safer lead creation flow and note attribution
  • Use response with explicit success checks, defensive lead_id extraction, final payload and created ID logging, and prepend agent attribution to notes when available
• Support owner on contact create/find
  • Add optional owner_id to create_contact and find_or_create_contact and set links.owner in the request payload
• Preserve note template line breaks in admin
  • Use sanitize_textarea_field specifically for note_template within sanitize_mapping_data to preserve newlines