Update wire protocol to version 6 and enhance timetable functionality

- Bumped the wire protocol version to 6, reflecting changes in the communication structure.
- Expanded the timetable API with new endpoints for fetching and managing lesson schedules, including `GET /api/schools/{id}/timetable` and `POST /api/schools/{id}/timetable/pin`.
- Updated the protocol documentation to include detailed descriptions of the new timetable features and message structures.
- Enhanced the client-side implementation to support the new timetable functionalities, including lesson pinning and unpinning.
- Revised server-side logic to handle timetable operations and ensure proper integration with existing school management features.
- Added tests to validate the new timetable functionalities and ensure robustness in handling lesson data.

tests/HSchool.AppHost.Tests/GameSocketTests.cs

@@ -1,3 +1,4 @@
+using System.Net.Http.Json;
 using System.Net.WebSockets;
 using HSchool.Protocol;
 
@@ -110,6 +111,8 @@ public class GameSocketTests(AppHostFixture fixture)
         Assert.Equal(16, classroom.PupilSlots);
         Assert.Contains(classroom.Items, item => item.Name == "Парта" && item.Count == 16);
         Assert.DoesNotContain(classroom.Items, item => item.Name == "Стул");
+        Assert.Equal("", classroom.ActivitySubject);
+        Assert.Empty(classroom.Present);
     }
 
     [Fact]
@@ -157,6 +160,40 @@ public class GameSocketTests(AppHostFixture fixture)
         Assert.DoesNotContain(snapshot.Nodes, node => node.Id == "corridor-1");
     }
 
+    [Fact]
+    public async Task OpeningASchoolDuringAMathLesson_PutsOccupancyOnTheRoom()
+    {
+        using var client = fixture.App.CreateHttpClient("server");
+        await SchoolApiTests.ResetAsync(client);
+        var start = new DateTime(2012, 4, 3, 10, 20, 0, DateTimeKind.Utc);
+        var school = await SchoolApiTests.CreateAsync(client, "Кто где сейчас", start);
+
+        var staffing = await client.GetFromJsonAsync<StaffingSnapshot>(
+            $"/api/schools/{school.Id}/staffing",
+            TestContext.Current.CancellationToken);
+        Assert.NotNull(staffing);
+        var applicant = staffing.Applicants[0];
+        using var hire = await client.PostAsJsonAsync(
+            $"/api/schools/{school.Id}/staff/hire",
+            new { personId = applicant.Id, position = "Teacher" },
+            TestContext.Current.CancellationToken);
+        hire.EnsureSuccessStatusCode();
+        using var assign = await client.PostAsJsonAsync(
+            $"/api/schools/{school.Id}/staff/{Uri.EscapeDataString(applicant.Id)}/subjects",
+            new { subject = "Mathematics" },
+            TestContext.Current.CancellationToken);
+        assign.EnsureSuccessStatusCode();
+
+        using var socket = await OpenSchoolAsync(school.Id);
+        var snapshot = ProtocolCodec.ReadMapSnapshot(await ReceiveUntilAsync(socket, MessageType.ServerMapSnapshot));
+        var occupied = Assert.Single(snapshot.Nodes, node => node.ActivitySubject.Length > 0);
+
+        Assert.Equal("Математика", occupied.ActivitySubject);
+        Assert.NotEmpty(occupied.ActivityClass);
+        Assert.Contains(applicant.FullName, occupied.Present);
+        Assert.True(occupied.Present.Count > 1);
+    }
+
     [Fact]
     public async Task Pausing_FreezesTheClock()
     {
@@ -448,7 +485,8 @@ public class GameSocketTests(AppHostFixture fixture)
         using var cts = CancellationTokenSource.CreateLinkedTokenSource(TestContext.Current.CancellationToken);
         cts.CancelAfter(timeout ?? DefaultTimeout);
 
-        var buffer = new byte[ProtocolConstants.MaxMessageSize];
+        var buffer = new byte[64 * 1024];
+        var chunks = new List<byte>();
 
         while (true)
         {
@@ -467,11 +505,22 @@ public class GameSocketTests(AppHostFixture fixture)
                 throw new InvalidOperationException($"Socket closed while waiting for {expected}: {socket.CloseStatus}.");
             }
 
-            var frame = buffer[..result.Count];
+            chunks.AddRange(buffer.AsSpan(0, result.Count).ToArray());
+            if (!result.EndOfMessage)
+            {
+                continue;
+            }
+
+            var frame = chunks.ToArray();
+            chunks.Clear();
             if (ProtocolCodec.PeekMessageType(frame) == expected)
             {
                 return frame;
             }
         }
     }
+
+    private sealed record StaffingSnapshot(IReadOnlyList<ApplicantSnapshot> Applicants);
+
+    private sealed record ApplicantSnapshot(string Id, string FullName);
 }