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.ClientModels/Resources/FieldsNameResource.Designer.cs

@@ -1,4 +1,4 @@
-//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
 // <auto-generated>
 //     This code was generated by a tool.
 //     Runtime Version:4.0.30319.42000
@@ -396,6 +396,30 @@ namespace PrivaPub.ClientModels.Resources {
         /// <summary>
         ///   Looks up a localized string similar to Name.
         /// </summary>
+        public static string AvatarId {
+            get {
+                return ResourceManager.GetString("AvatarId", resourceCulture);
+            }
+        }
+        
+        public static string Biography {
+            get {
+                return ResourceManager.GetString("Biography", resourceCulture);
+            }
+        }
+        
+        public static string LanguageCode {
+            get {
+                return ResourceManager.GetString("LanguageCode", resourceCulture);
+            }
+        }
+        
+        public static string UserName {
+            get {
+                return ResourceManager.GetString("UserName", resourceCulture);
+            }
+        }
+        
         public static string Name {
             get {
                 return ResourceManager.GetString("Name", resourceCulture);