feat: Add support for 2018 client API endpoints and data models

- Implemented new search endpoints for rooms to accommodate the 2018 client.
- Added support for retrieving room details and featured rooms in a format compatible with the 2018 client.
- Introduced new data models for login responses and player presence specific to the 2018 client.
- Created mappers to convert between internal entities and the 2018 wire formats for players and rooms.
- Updated existing storefront APIs to include versioned endpoints for the 2018 client.
- Enhanced the version controller to return dual-format responses for compatibility with both 2018 and 2020 clients.
- Refactored the configuration service to ensure trailing slashes in URLs for the 2018 client.

DorkNet.Models/Players/Presence2018.cs

@@ -0,0 +1,21 @@
+using System.Text.Json.Serialization;
+
+namespace DorkNet.Models.Players;
+
+/// <summary>
+/// June-2018 presence record returned from POST api/presence/v2/list.
+/// Keys verified from RecNet.DBHHFILLFLC.Deserialize: PlayerId (long),
+/// IsOnline (bool), GameSession (optional object — null when the player is
+/// online but not in a session; the client null-checks it).
+/// </summary>
+public class Presence2018
+{
+    [JsonPropertyName("PlayerId")]
+    public long PlayerId { get; set; }
+
+    [JsonPropertyName("IsOnline")]
+    public bool IsOnline { get; set; }
+
+    [JsonPropertyName("GameSession")]
+    public object? GameSession { get; set; }
+}