refactor: clean up presentation layer — AppState grouping, multipart extractor, thin handlers

crates/presentation/src/handlers/auth.rs

@@ -28,7 +28,7 @@ pub async fn register(
         email: req.email,
         password: req.password,
     };
-    let user = state.register_handler.execute(cmd).await?;
+    let user = state.identity.register.execute(cmd).await?;
     let token = state
         .token_issuer
         .issue(&user.id, "user")
@@ -59,7 +59,7 @@ pub async fn login(
         email: req.email,
         password: req.password,
     };
-    let (user, token) = state.login_handler.execute(cmd).await?;
+    let (user, token) = state.identity.login.execute(cmd).await?;
     Ok(Json(AuthResponse {
         token,
         user: UserResponse::from_domain(&user),
@@ -81,6 +81,6 @@ pub async fn me(
     let query = GetProfileQuery {
         user_id: claims.user_id,
     };
-    let user = state.get_profile_handler.execute(query).await?;
+    let user = state.identity.get_profile.execute(query).await?;
     Ok(Json(UserResponse::from_domain(&user)))
 }