Added transcription of audio and video files to local data sources (#1081)

Co-authored-by: Paul Koudelka <106623909+PaulKoudelka@users.noreply.github.com>

app/MindWork AI Studio/Tools/FileContentHash.cs

@@ -0,0 +1,28 @@
+using System.Security.Cryptography;
+
+namespace AIStudio.Tools;
+
+/// <summary>
+/// Computes the hash of the content of a file.
+/// </summary>
+internal static class FileContentHash
+{
+    /// <summary>
+    /// Computes a lowercase SHA-256 hash for a file without loading it fully into memory.
+    /// </summary>
+    /// <param name="path">The file path.</param>
+    /// <param name="token">The cancellation token.</param>
+    /// <returns>The lowercase hexadecimal hash.</returns>
+    internal static async Task<string> ComputeAsync(string path, CancellationToken token)
+    {
+        await using var stream = new FileStream(
+            path,
+            FileMode.Open,
+            FileAccess.Read,
+            FileShare.Read,
+            65_536,
+            FileOptions.Asynchronous | FileOptions.SequentialScan);
+
+        return Convert.ToHexStringLower(await SHA256.HashDataAsync(stream, token));
+    }
+}