fix(auth): also accept 'name' field for signup compatibility

Frontend sends 'name' field directly. RegisterPayload now accepts:
- name (direct, used by frontend)
- full_name (legacy)
- first_name + last_name (new format)

apps/users/src/handlers/auth.rs

@@ -41,6 +41,8 @@ pub struct RegisterPayload {
     pub last_name:  Option<String>,
     #[serde(default)]
     pub full_name: Option<String>,
+    #[serde(default)]
+    pub name: Option<String>,
     pub email:     String,
     pub phone:     Option<String>,
     pub password:  String,
@@ -202,10 +204,11 @@ async fn register(
     let password_hash = hash_password(&payload.password)
         .map_err(|e| err(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string(), "INTERNAL_ERROR"))?;
 
-    let full_name = match (&payload.first_name, &payload.last_name, &payload.full_name) {
-        (Some(fn_), Some(ln_), _) => format!("{} {}", fn_.trim(), ln_.trim()).trim().to_string(),
-        (_, _, Some(fn_)) => fn_.trim().to_string(),
-        _ => return Err(err(StatusCode::UNPROCESSABLE_ENTITY, "first_name and last_name are required", "VALIDATION_ERROR")),
+    let full_name = match (&payload.first_name, &payload.last_name, &payload.full_name, &payload.name) {
+        (Some(fn_), Some(ln_), _, _) => format!("{} {}", fn_.trim(), ln_.trim()).trim().to_string(),
+        (_, _, Some(fn_), _) => fn_.trim().to_string(),
+        (_, _, _, Some(n)) => n.trim().to_string(),
+        _ => return Err(err(StatusCode::UNPROCESSABLE_ENTITY, "Name is required (full_name or first_name+last_name)", "VALIDATION_ERROR")),
     };
 
     let user = UserRepository::create(&state.pool, CreateUserPayload {