feat(server)!: require a logged-in account for every channel request

Drop unauthenticated guests from channels: the allow_guests setting, the
/guests endpoints and the guest seat table are gone, and requests without an
account session get 401 account_required. Share links are unaffected.
Contract version is now 8.0.0.

server/tests/WebDrop.Api.Tests/StreamingTests.cs

@@ -20,7 +20,8 @@ public class StreamingTests(ServerFixture s) : IClassFixture<ServerFixture>
         ws.Options.AddSubProtocol($"wd.role.{who.Role}");
         if (who.Token is not null) ws.Options.AddSubProtocol($"wd.auth.{B64(who.Token)}");
         ws.Options.AddSubProtocol($"wd.ep.{B64(who.EndpointSecret)}");
-        if (who.Role == "owner") ws.Options.AddSubProtocol($"wd.account.{B64(Convert.FromBase64String(s.OwnerAccountToken))}");
+        string account = who.AccountToken ?? (who.Role == "owner" ? s.OwnerAccountToken : s.MemberAccountToken);
+        ws.Options.AddSubProtocol($"wd.account.{B64(Convert.FromBase64String(account))}");
 
         var uri = new UriBuilder(s.BaseUri) { Scheme = "ws", Path = $"/api/v1/channels/{ch.Id}/ws", Query = $"from={from}" }.Uri;
         using var cts = new CancellationTokenSource(Timeout);
@@ -106,23 +107,22 @@ public class StreamingTests(ServerFixture s) : IClassFixture<ServerFixture>
         var ex = await Assert.ThrowsAsync<WebSocketException>(() => ConnectWs(ch, bad));
         Assert.Contains("401", ex.Message);
 
-        // 未入席
+        // 未入席(已登录,但还不是成员)
         var stranger = new Who("write", ch.WriteToken, new byte[32]);
         var ex2 = await Assert.ThrowsAsync<WebSocketException>(() => ConnectWs(ch, stranger));
         Assert.Contains("403", ex2.Message);
     }
 
     [Fact]
-    public async Task WebSocketNotifiesSeatChangesAndClosesWhenRevoked()
+    public async Task WebSocketNotifiesMemberChangesAndClosesWhenRevoked()
     {
         var ch = await s.CreateAsync();
         await s.JoinAsync(ch, ch.Member);
-        string memberHash = B64(System.Security.Cryptography.SHA256.HashData(ch.Member.EndpointSecret));
 
         using var member = await ConnectWs(ch, ch.Member);
 
-        // 所有者释放席位:订阅者先收到 seats 控制消息,随后被以 not_joined 关闭
-        using var release = await s.Http.SendAsync(s.Req(HttpMethod.Delete, $"/api/v1/channels/{ch.Id}/guests/{memberHash}", ch.Owner));
+        // 所有者撤销成员:订阅者先收到 members 控制消息,随后被以 not_joined 关闭
+        using var release = await s.Http.SendAsync(s.Req(HttpMethod.Delete, $"/api/v1/channels/{ch.Id}/invitations/fixture_member", ch.Owner));
         Assert.Equal(HttpStatusCode.NoContent, release.StatusCode);
 
         bool closed = false;