Updates a company. The set of writable attributes depends on the caller's
role and the company's verification_status:

• Company owners/admins can update name, address, interests, referral
  fields, and (while KYC is pending/rejected/unset) the KYC document and
  profile fields (fantasy_name, commercial_business, contact_phone,
  contact_email, commercial_type, constitution_date, legal_address,
  economic_activities, and the KYC file fields).
• Once verification_status is approved, only the signed-contract flags
  (plh_contract_file_signed, plh_kyc_file_signed,
  plh_alliance_file_signed) remain writable by company users.
• Members can also submit nested company_memberships updates (role, legal
  representative, powers, partner, participation rate).
• A large set of commercial/financial attributes is writable only by
  Cardda staff and is intentionally omitted here.

Non-privileged callers receive an empty permitted set (no-op update).