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/ServerFixture.cs

@@ -23,6 +23,8 @@ public sealed class ServerFixture : IAsyncLifetime, IAsyncDisposable
     public HttpClient Http { get; private set; } = null!;
     public Uri BaseUri { get; private set; } = null!;
     public string OwnerAccountToken { get; private set; } = null!;
+    /// <summary>非所有者的默认账号。频道只接受登录账号,所以测试里的「成员」「读者」都是这个账号。</summary>
+    public string MemberAccountToken { get; private set; } = null!;
 
     public ServerFixture() : this([]) { }
 
@@ -47,12 +49,20 @@ public sealed class ServerFixture : IAsyncLifetime, IAsyncDisposable
         string address = App.Services.GetRequiredService<IServer>().Features.Get<IServerAddressesFeature>()!.Addresses.First();
         BaseUri = new Uri(address);
         Http = new HttpClient { BaseAddress = BaseUri, Timeout = TimeSpan.FromSeconds(30) };
+        var accounts = App.Services.GetRequiredService<SqliteAccountStore>();
+        OwnerAccountToken = NewAccountToken("fixture_owner");
+        MemberAccountToken = NewAccountToken("fixture_member");
+    }
+
+    /// <summary>注册一个账号并返回它的会话令牌。</summary>
+    public string NewAccountToken(string username)
+    {
         var accounts = App.Services.GetRequiredService<SqliteAccountStore>();
         var verifier = RandomNumberGenerator.GetBytes(32);
         using var key = ECDiffieHellman.Create(ECCurve.NamedCurves.nistP256);
         var point = key.ExportParameters(false).Q;
-        accounts.Register("fixture_owner", RandomNumberGenerator.GetBytes(16), verifier, new byte[28], JsonSerializer.Serialize(new { kty = "EC", crv = "P-256", x = B64(point.X!), y = B64(point.Y!) }));
-        OwnerAccountToken = accounts.Authenticate("fixture_owner", verifier)!;
+        accounts.Register(username, RandomNumberGenerator.GetBytes(16), verifier, new byte[28], JsonSerializer.Serialize(new { kty = "EC", crv = "P-256", x = B64(point.X!), y = B64(point.Y!) }));
+        return accounts.Authenticate(username, verifier)!;
     }
 
     public async Task DisposeAsync()
@@ -82,7 +92,8 @@ public sealed class ServerFixture : IAsyncLifetime, IAsyncDisposable
         public Who Reader => new("read", ReadToken, MemberSecret);
     }
 
-    public sealed record Who(string Role, byte[]? Token, byte[] EndpointSecret);
+    /// <summary>AccountToken 为空时:所有者用 OwnerAccountToken,其余用 MemberAccountToken。</summary>
+    public sealed record Who(string Role, byte[]? Token, byte[] EndpointSecret, string? AccountToken = null);
 
     public static string B64(byte[] bytes) => Codec.Encode(bytes);
     public static string NewId() => B64(RandomNumberGenerator.GetBytes(16));
@@ -93,7 +104,10 @@ public sealed class ServerFixture : IAsyncLifetime, IAsyncDisposable
         req.Headers.Add("X-WD-Role", who.Role);
         if (who.Token is not null) req.Headers.Authorization = new AuthenticationHeaderValue("Bearer", B64(who.Token));
         req.Headers.Add("X-WD-Endpoint", B64(who.EndpointSecret));
-        if (who.Role == "owner") req.Headers.Add("X-WD-Account", OwnerAccountToken);
+        // 频道和空间只接受登录账号;便捷分享(/shares)仍由未登录终端使用
+        if (path.StartsWith("/api/v1/channels", StringComparison.Ordinal) || path.StartsWith("/api/v1/spaces", StringComparison.Ordinal))
+            req.Headers.Add("X-WD-Account", who.AccountToken ?? (who.Role == "owner" ? OwnerAccountToken : MemberAccountToken));
+        else if (who.Role == "owner") req.Headers.Add("X-WD-Account", OwnerAccountToken);
         return req;
     }
 
@@ -118,7 +132,7 @@ public sealed class ServerFixture : IAsyncLifetime, IAsyncDisposable
         };
         if (mode == ChannelMode.Enc) body["read_hash"] = B64(TokenHash.Compute(ch.ReadToken));
         // General transport tests explicitly use open spaces; creation defaults have separate coverage.
-        body["settings"] = settings ?? new { name = "Test space", max_members = 2, join_policy = "open", allow_guests = true };
+        body["settings"] = settings ?? new { name = "Test space", max_members = 2, join_policy = "open" };
 
         using var req = Req(HttpMethod.Post, "/api/v1/channels", ch.Owner, JsonBody(body));
         if (capToken is not null) req.Headers.Add("X-WD-Cap", capToken);