Adds Tesla API integration

Adds an endpoint to interact with the Tesla API via a command proxy.

This includes fetching vehicle information and configuring telemetry settings. It introduces new models to represent the Tesla API responses and request structures.

Source/ProofOfConcept/Models/VehiclesResponse.cs

@@ -0,0 +1,29 @@
+namespace ProofOfConcept.Models;
+
+using System.Text.Json.Serialization;
+
+public sealed class VehiclesEnvelope
+{
+    [JsonPropertyName("response")]
+    public List<VehicleSummary> Response { get; set; } = new();
+
+    [JsonPropertyName("count")]
+    public int Count { get; set; }
+}
+
+public sealed class VehicleSummary
+{
+    // Tesla fields commonly present on /api/1/vehicles
+    [JsonPropertyName("id")]           public long Id { get; set; }
+    [JsonPropertyName("vehicle_id")]   public long VehicleId { get; set; }
+    [JsonPropertyName("vin")]          public string? Vin { get; set; }
+    [JsonPropertyName("display_name")] public string? DisplayName { get; set; }
+    [JsonPropertyName("state")]        public string? State { get; set; }
+
+    // Extra fields sometimes included; safe to keep nullable
+    [JsonPropertyName("in_service")]   public bool? InService { get; set; }
+    [JsonPropertyName("calendar_enabled")] public bool? CalendarEnabled { get; set; }
+    [JsonPropertyName("id_s")]         public string? IdS { get; set; }
+    [JsonPropertyName("option_codes")] public string? OptionCodes { get; set; }
+    [JsonPropertyName("color")]        public string? Color { get; set; }
+}