- Add DDHH_JM_ACF_Fields class with register_fields() method
- Field group 'Job Details' for post_type job_offer
- 6 fields: job_location (text, required), job_type (select, required),
job_deadline (date_picker), job_contact_email (email, required),
job_logo (image), job_deactivation_reason (textarea, conditional)
- German labels: Standort, Art, Bewerbungsfrist, Kontakt-E-Mail, Logo
- Logo returns ID for media library integration
- Deactivation reason field shows only when status != publish
- Hooked to 'acf/init' action
