Enhance TMDb metadata handling with bearer token support and update .env.example documentation

Updated the TMDb metadata provider to support both API key and bearer token authentication methods, improving flexibility in API requests. Refactored the GetAsync and TryGetAsync methods to accept an optional bearer token parameter. Additionally, clarified the .env.example file to provide detailed instructions on using TMDb's authentication methods, ensuring users understand how to configure their API access correctly.

backend/tests/TeleWave.Application.Tests/Metadata/TmdbAuthTests.cs

@@ -0,0 +1,72 @@
+using System.Net;
+using System.Text;
+using Microsoft.Extensions.Options;
+using TeleWave.Infrastructure.Metadata;
+using Xunit;
+
+namespace TeleWave.Application.Tests.Metadata;
+
+/// <summary>
+/// TMDb принимает и ключ v3 (в query), и токен v4 (в заголовке). Способ выбирается по форме самого
+/// значения, поэтому проверяем именно то, что уходит в запрос.
+/// </summary>
+public class TmdbAuthTests
+{
+    [Fact]
+    public async Task V3Key_GoesToQuery()
+    {
+        var handler = new CapturingHandler();
+        var provider = ProviderWith("fa38966b51f0043827fa89a5e42a0afe", handler);
+
+        await provider.GetSeasonNumbersAsync("123", CancellationToken.None);
+
+        var request = handler.Last!;
+        Assert.Contains("api_key=fa38966b51f0043827fa89a5e42a0afe", request.RequestUri!.Query);
+        Assert.Null(request.Headers.Authorization);
+    }
+
+    [Fact]
+    public async Task V4Token_GoesToAuthorizationHeader()
+    {
+        var handler = new CapturingHandler();
+        var token = "eyJhbGciOiJIUzI1NiJ9.eyJhdWQiOiJ0ZWxld2F2ZSJ9.c2lnbmF0dXJl";
+        var provider = ProviderWith(token, handler);
+
+        await provider.GetSeasonNumbersAsync("123", CancellationToken.None);
+
+        var request = handler.Last!;
+        Assert.DoesNotContain("api_key", request.RequestUri!.Query);
+        Assert.Equal("Bearer", request.Headers.Authorization?.Scheme);
+        Assert.Equal(token, request.Headers.Authorization?.Parameter);
+    }
+
+    private static TmdbMetadataProvider ProviderWith(string apiKey, HttpMessageHandler handler) =>
+        new(
+            new SingleClientFactory(handler),
+            Options.Create(new MetadataOptions { Tmdb = new TmdbOptions { ApiKey = apiKey } })
+        );
+
+    private sealed class CapturingHandler : HttpMessageHandler
+    {
+        public HttpRequestMessage? Last { get; private set; }
+
+        protected override Task<HttpResponseMessage> SendAsync(
+            HttpRequestMessage request,
+            CancellationToken cancellationToken
+        )
+        {
+            Last = request;
+            return Task.FromResult(
+                new HttpResponseMessage(HttpStatusCode.OK)
+                {
+                    Content = new StringContent("{}", Encoding.UTF8, "application/json"),
+                }
+            );
+        }
+    }
+
+    private sealed class SingleClientFactory(HttpMessageHandler handler) : IHttpClientFactory
+    {
+        public HttpClient CreateClient(string name) => new(handler, disposeHandler: false);
+    }
+}