net10, the refactor finished, and federation that works

The tree had not compiled since its first commit: Group, DmGroup and
IGroupUsersService were referenced and never written, an IDE rename had
turned the user-settings DTO into the ViewAvatarServer enum, and the settings
were saved as an entity they no longer were.

Built now:
- Group (an ActivityPub Group actor with its own keys, members, invitation
  code and optional password) and DmGroup (a conversation), with
  /clientapi/group/{list,insert,update,join,leave,approve}.
- Posts and DMs: /clientapi/post/{list,insert,delete}, /clientapi/dm/{list,insert};
  DM recipients are local usernames or user@host handles resolved by WebFinger.
- Invitation sign-up and login against the group's invitation code, checking
  the password before any account is created.
- Federation: WebFinger, NodeInfo 2.0, actors at /peasants/{name} (Person,
  Group, and an Application instance actor) with SPKI keys, draft-cavage
  RSA-SHA256 HTTP signatures both ways, an inbox handling Follow (+Accept),
  Undo, Create, Delete and Update, an outbox, notes at /posts/{id}, and a
  persisted, retried, signed delivery queue. A post to a group is announced
  by the group to its followers (FEP-1b12).
- The unused, broken typed ActivityPub models are replaced by a renderer;
  NSign's HMAC setup, which could not federate, is gone.

Upgrade: net10.0, MongoDB.Entities 25.1 (instance DB API, Standard GUIDs),
Swashbuckle 10 / OpenApi 2, Serilog.AspNetCore 10, MailKit 4.18,
PasswordGenerator 3. The JWT keys are 64 bytes (IdentityModel 8 refuses
shorter for HS512). Production runs its own mongod on 127.0.0.1:27022, as
Sintopia's apps do, and deploys to privapub.thepra.dev from the build runner.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

PrivaPub/Extensions/Extensions.cs

@@ -1,16 +1,8 @@
-using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Authorization;
 
-using Org.BouncyCastle.Asn1.X509;
-using Org.BouncyCastle.Crypto.Generators;
-using Org.BouncyCastle.Crypto.Prng;
-using Org.BouncyCastle.Crypto;
-using Org.BouncyCastle.Security;
-using Org.BouncyCastle.X509;
 
 using PrivaPub.ClientModels;
 
-using System.Security.Cryptography.X509Certificates;
-using Org.BouncyCastle.Math;
 using PrivaPub.Models.User;
 using System.Security.Claims;
 
@@ -18,15 +10,6 @@ namespace PrivaPub.Extensions
 {
 	public static class Extensions
 	{
-		public static string GetLogsConnectionString(this IConfiguration configuration) =>
-			configuration.GetSection("Serilog")
-						?.GetSection("WriteTo")
-						?.GetChildren()
-						?.First()
-						?.GetSection("Args")
-						?.GetSection("databaseUrl")
-						?.Value;
-
 		public static AuthorizationPolicy IsAdminPolicy() =>
 			new AuthorizationPolicyBuilder().RequireAuthenticatedUser()
 																			.RequireClaim(Policies.IsAdmin, true.ToString().ToLower())
@@ -51,42 +34,14 @@ namespace PrivaPub.Extensions
 		public static string GetHost(this HttpContext httpContext) =>
 			$"https://{httpContext.Request.Host}";
 
-		public static X509Certificate2 GetX509Certificate2(string certName)
-		{
-			var keypairgen = new RsaKeyPairGenerator();
-			keypairgen.Init(new KeyGenerationParameters(new SecureRandom(new CryptoApiRandomGenerator()), 512));
-
-			var keypair = keypairgen.GenerateKeyPair();
-
-			var gen = new X509V3CertificateGenerator();
-
-			var CN = new X509Name("CN=" + certName);
-			var SN = BigInteger.ProbablePrime(120, new Random());
-
-			gen.SetSerialNumber(SN);
-			gen.SetSubjectDN(CN);
-			gen.SetIssuerDN(CN);
-			gen.SetNotAfter(DateTime.MaxValue);
-			gen.SetNotBefore(DateTime.Now.Subtract(new TimeSpan(7, 0, 0, 0)));
-			gen.SetSignatureAlgorithm("MD5WithRSA");
-			gen.SetPublicKey(keypair.Public);
-
-			var newCert = gen.Generate(keypair.Private);
-
-			return new X509Certificate2(DotNetUtilities.ToX509Certificate((Org.BouncyCastle.X509.X509Certificate)newCert));
-		}
-
 		public static UserPolicyType GetHighestPolicy(this ClaimsPrincipal claimsPrincipal)
 		{
-			if (bool.Parse(claimsPrincipal.FindFirstValue(Policies.IsAdmin)))
+			if (claimsPrincipal.FindFirstValue(Policies.IsAdmin) == "true")
 				return UserPolicyType.IsAdmin;
 
-			if (bool.Parse(claimsPrincipal.FindFirstValue(Policies.IsModerator)))
+			if (claimsPrincipal.FindFirstValue(Policies.IsModerator) == "true")
 				return UserPolicyType.IsModerator;
 
-			if (bool.Parse(claimsPrincipal.FindFirstValue(Policies.IsUser)))
-				return UserPolicyType.IsUser;
-
 			return UserPolicyType.IsUser;
 		}
 	}