feat(01-03): register ACF field group for job_offer metadata

- 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

includes/class-acf-fields.php

@@ -0,0 +1,115 @@
+<?php
+/**
+ * ACF field groups handler
+ *
+ * @package DDHH_Job_Manager
+ */
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit;
+
+/**
+ * Handles ACF field group registration
+ */
+class DDHH_JM_ACF_Fields {
+
+	/**
+	 * Register ACF field groups
+	 * Hooked to 'acf/init'
+	 */
+	public static function register_fields() {
+		// Check if ACF Pro is available
+		if ( ! function_exists( 'acf_add_local_field_group' ) ) {
+			return;
+		}
+
+		// Register Job Details field group
+		acf_add_local_field_group(
+			array(
+				'key'      => 'group_job_details',
+				'title'    => __( 'Job Details', 'ddhh-job-manager' ),
+				'fields'   => array(
+					// Job Location
+					array(
+						'key'      => 'field_job_location',
+						'label'    => __( 'Standort', 'ddhh-job-manager' ),
+						'name'     => 'job_location',
+						'type'     => 'text',
+						'required' => 1,
+					),
+					// Job Type
+					array(
+						'key'      => 'field_job_type',
+						'label'    => __( 'Art', 'ddhh-job-manager' ),
+						'name'     => 'job_type',
+						'type'     => 'select',
+						'required' => 1,
+						'choices'  => array(
+							'vollzeit'  => __( 'Vollzeit', 'ddhh-job-manager' ),
+							'teilzeit'  => __( 'Teilzeit', 'ddhh-job-manager' ),
+							'ehrenamt'  => __( 'Ehrenamt', 'ddhh-job-manager' ),
+						),
+					),
+					// Job Deadline
+					array(
+						'key'           => 'field_job_deadline',
+						'label'         => __( 'Bewerbungsfrist', 'ddhh-job-manager' ),
+						'name'          => 'job_deadline',
+						'type'          => 'date_picker',
+						'required'      => 0,
+						'return_format' => 'Y-m-d',
+						'display_format' => 'd.m.Y',
+					),
+					// Job Contact Email
+					array(
+						'key'      => 'field_job_contact_email',
+						'label'    => __( 'Kontakt-E-Mail', 'ddhh-job-manager' ),
+						'name'     => 'job_contact_email',
+						'type'     => 'email',
+						'required' => 1,
+					),
+					// Job Logo
+					array(
+						'key'           => 'field_job_logo',
+						'label'         => __( 'Logo', 'ddhh-job-manager' ),
+						'name'          => 'job_logo',
+						'type'          => 'image',
+						'required'      => 0,
+						'return_format' => 'id',
+						'preview_size'  => 'thumbnail',
+						'library'       => 'all',
+					),
+					// Job Deactivation Reason (internal, admin-only)
+					array(
+						'key'               => 'field_job_deactivation_reason',
+						'label'             => __( 'Deaktivierungsgrund (intern)', 'ddhh-job-manager' ),
+						'name'              => 'job_deactivation_reason',
+						'type'              => 'textarea',
+						'required'          => 0,
+						'rows'              => 3,
+						'conditional_logic' => array(
+							array(
+								array(
+									'field'    => 'post_status',
+									'operator' => '!=',
+									'value'    => 'publish',
+								),
+							),
+						),
+					),
+				),
+				'location' => array(
+					array(
+						array(
+							'param'    => 'post_type',
+							'operator' => '==',
+							'value'    => 'job_offer',
+						),
+					),
+				),
+				'position' => 'normal',
+				'style'    => 'default',
+			)
+		);
+	}
+}