Clean up namespaces (#410)

No meaningful code changes, just lots of namespace shuffling to have fewer namespaces and to put things in better namespaces.

src/ModelContextProtocol/Protocol/TextResourceContents.cs

@@ -0,0 +1,29 @@
+using System.Text.Json.Serialization;
+
+namespace ModelContextProtocol.Protocol;
+
+/// <summary>
+/// Represents text-based contents of a resource in the Model Context Protocol.
+/// </summary>
+/// <remarks>
+/// <para>
+/// <see cref="TextResourceContents"/> is used when textual data needs to be exchanged through
+/// the Model Context Protocol. The text is stored directly in the <see cref="Text"/> property.
+/// </para>
+/// <para>
+/// This class inherits from <see cref="ResourceContents"/>, which also has a sibling implementation
+/// <see cref="BlobResourceContents"/> for binary resources. When working with resources, the
+/// appropriate type is chosen based on the nature of the content.
+/// </para>
+/// <para>
+/// See the <see href="https://github.com/modelcontextprotocol/specification/blob/main/schema/">schema</see> for more details.
+/// </para>
+/// </remarks>
+public class TextResourceContents : ResourceContents
+{
+    /// <summary>
+    /// Gets or sets the text of the item.
+    /// </summary>
+    [JsonPropertyName("text")]
+    public string Text { get; set; } = string.Empty;
+}