Replace weather example with shared YouTube models

Removed WeatherForecast API and model. Added TuneRipper.Shared project with shared configuration and YouTube processing models. Updated solution and project references to enable code sharing between API and client. Explicitly included Controllers folder in API project.

TuneRipper.Shared/Models/ProcessVideoModels.cs

@@ -0,0 +1,24 @@
+namespace TuneRipper.Shared.Models;
+
+public class ProcessVideoRequest
+{
+    public string? Url { get; set; }
+    public string? Format { get; set; } = "mp3";
+    public string? Quality { get; set; } = "128";
+}
+
+public class ProcessVideoResponse
+{
+    public bool Success { get; set; }
+    public string? Message { get; set; }
+    public string? FileName { get; set; }
+    public string? DownloadUrl { get; set; }
+    public YouTubeVideoDetails? VideoDetails { get; set; }
+}
+
+public class DownloadProgress
+{
+    public int PercentageComplete { get; set; }
+    public string? Status { get; set; }
+    public string? Message { get; set; }
+}

TuneRipper.Shared/Models/YouTubeVideoDetails.cs

@@ -0,0 +1,14 @@
+namespace TuneRipper.Shared.Models;
+
+public class YouTubeVideoDetails
+{
+    public string? Id { get; set; }
+    public string? Title { get; set; }
+    public string? Description { get; set; }
+    public string? ThumbnailUrl { get; set; }
+    public TimeSpan Duration { get; set; }
+    public string? Author { get; set; }
+    public int ViewCount { get; set; }
+    public DateTime UploadDate { get; set; }
+    public List<string> Tags { get; set; } = new();
+}