refactor!: rename the project from Monitor to MoShiro

Namespaces, assemblies, projects and directories, the solution, binaries,
images, systemd units, config paths, environment variables, protocol method
names, the media type and the raw chunk magic all move to MoShiro/moshiro.
Existing data and deployments are not compatible and must be recreated.
Also fix the architecture tests after the solution layout change and make
the update tests independent of their order.

backend/tests/MoShiro.Backend.Tests/SseClient.cs

@@ -0,0 +1,103 @@
+using System.Collections.Concurrent;
+using System.Text.Json.Nodes;
+
+namespace MoShiro.Backend.Tests;
+
+public sealed record SseEvent(string Name, JsonNode? Data);
+
+/// <summary>读取 text/event-stream：把事件和心跳注释收集起来，测试按条件等待。</summary>
+public sealed class SseClient : IAsyncDisposable
+{
+    private readonly HttpResponseMessage _response;
+    private readonly CancellationTokenSource _stop = new();
+    private readonly Task _reader;
+
+    private SseClient(HttpResponseMessage response, Stream stream)
+    {
+        _response = response;
+        _reader = Task.Run(() => ReadAsync(stream));
+    }
+
+    public ConcurrentQueue<SseEvent> Events { get; } = new();
+
+    private int _comments;
+
+    public int Comments => Volatile.Read(ref _comments);
+
+    public string? ContentType => _response.Content.Headers.ContentType?.MediaType;
+
+    public static async Task<SseClient> ConnectAsync(HttpClient http, string url)
+    {
+        HttpResponseMessage response = await http.GetAsync(url, HttpCompletionOption.ResponseHeadersRead);
+        response.EnsureSuccessStatusCode();
+        return new SseClient(response, await response.Content.ReadAsStreamAsync());
+    }
+
+    public async Task<SseEvent> WaitForAsync(Func<SseEvent, bool> predicate, TimeSpan? timeout = null)
+    {
+        long started = TimeProvider.System.GetTimestamp();
+        TimeSpan limit = timeout ?? TimeSpan.FromSeconds(15);
+        while (TimeProvider.System.GetElapsedTime(started) < limit)
+        {
+            SseEvent? found = Events.ToArray().FirstOrDefault(predicate);
+            if (found is not null)
+            {
+                return found;
+            }
+
+            await Task.Delay(25);
+        }
+
+        throw new TimeoutException("the expected server-sent event never arrived; got: " + string.Join(", ", Events.Select(e => e.Name)));
+    }
+
+    public async ValueTask DisposeAsync()
+    {
+        await _stop.CancelAsync();
+        _response.Dispose();
+        try
+        {
+            await _reader;
+        }
+        catch (Exception ex) when (ex is OperationCanceledException or IOException or ObjectDisposedException)
+        {
+            // 连接被关闭
+        }
+
+        _stop.Dispose();
+    }
+
+    private async Task ReadAsync(Stream stream)
+    {
+        using var reader = new StreamReader(stream);
+        string? name = null;
+        var data = new System.Text.StringBuilder();
+        while (!_stop.IsCancellationRequested)
+        {
+            string? line = await reader.ReadLineAsync(_stop.Token);
+            if (line is null)
+            {
+                return;
+            }
+
+            if (line.StartsWith(':'))
+            {
+                Interlocked.Increment(ref _comments);
+            }
+            else if (line.StartsWith("event: ", StringComparison.Ordinal))
+            {
+                name = line["event: ".Length..];
+            }
+            else if (line.StartsWith("data: ", StringComparison.Ordinal))
+            {
+                data.Append(line["data: ".Length..]);
+            }
+            else if (line.Length == 0 && name is not null)
+            {
+                Events.Enqueue(new SseEvent(name, JsonNode.Parse(data.ToString())));
+                name = null;
+                data.Clear();
+            }
+        }
+    }
+}