feat: add profile fields for local users

DB→domain→API→AP→frontend end-to-end. Fields stored as
JSONB, exposed via PATCH /users/me, serialized as AP
PropertyValue attachment. Editor in federation settings,
display on profile card.

crates/presentation/src/handlers/auth.rs

@@ -1,7 +1,7 @@
 use crate::{deps_struct, errors::ApiError, extractors::Deps};
 use api_types::{
     requests::{LoginRequest, RegisterRequest},
-    responses::{AuthResponse, ErrorResponse, UserResponse},
+    responses::{AuthResponse, ErrorResponse, ProfileField, UserResponse},
 };
 use application::use_cases::auth::{login, register, LoginInput, RegisterInput};
 use axum::{http::StatusCode, response::IntoResponse, Json};
@@ -23,6 +23,14 @@ pub fn to_user_response(u: &domain::models::user::User) -> UserResponse {
         avatar_url: u.avatar_url.clone(),
         header_url: u.header_url.clone(),
         custom_css: u.custom_css.clone(),
+        profile_fields: u
+            .profile_fields
+            .iter()
+            .map(|(n, v)| ProfileField {
+                name: n.clone(),
+                value: v.clone(),
+            })
+            .collect(),
         local: u.local,
         is_followed_by_viewer: false,
         created_at: u.created_at,

crates/presentation/src/handlers/users/mod.rs

@@ -114,6 +114,9 @@ pub async fn patch_profile(
             avatar_url: body.avatar_url,
             header_url: body.header_url,
             custom_css: body.custom_css,
+            profile_fields: body
+                .profile_fields
+                .map(|f| f.into_iter().map(|pf| (pf.name, pf.value)).collect()),
         },
     )
     .await?;
@@ -208,6 +211,7 @@ pub async fn get_users(
             avatar_url: u.avatar_url.clone(),
             header_url: None,
             custom_css: None,
+            profile_fields: vec![],
             local: true,
             is_followed_by_viewer: false,
             created_at: chrono::Utc::now(),