Use DTOs to return API requests instead of Database Schema types.

Make use of IHttpStatusCodeResults

API/Controllers/DTOs/PeriodicWorker.cs

@@ -0,0 +1,33 @@
+using System.ComponentModel;
+using System.ComponentModel.DataAnnotations;
+using API.Workers;
+
+namespace API.Controllers.DTOs;
+
+/// <summary>
+/// <see cref="IPeriodic"/> DTO (<seealso cref="Worker"/> <seealso cref="BaseWorker"/>)
+/// </summary>
+public sealed record PeriodicWorker(string Key, IEnumerable<string> Dependencies, IEnumerable<string> MissingDependencies, bool DependenciesFulfilled, WorkerExecutionState State, DateTime LastExecution, TimeSpan Interval, DateTime NextExecution)
+    : Worker(Key, Dependencies, MissingDependencies, DependenciesFulfilled, State)
+{
+    /// <summary>
+    /// Timestamp when Worker executed last.
+    /// </summary>
+    [Required]
+    [Description("Timestamp when Worker executed last.")]
+    public DateTime LastExecution { get; init; } = LastExecution;
+    
+    /// <summary>
+    /// Interval at which Worker runs.
+    /// </summary>
+    [Required]
+    [Description("Interval at which Worker runs.")]
+    public TimeSpan Interval { get; init; } = Interval;
+    
+    /// <summary>
+    /// Timestamp when Worker is scheduled to execute next.
+    /// </summary>
+    [Required]
+    [Description("Timestamp when Worker is scheduled to execute next.")]
+    public DateTime NextExecution { get; init; } = LastExecution;
+}