feat: add activity feed/users/profile use cases and port methods

crates/application/src/use_cases/get_users.rs

@@ -0,0 +1,9 @@
+use domain::{errors::DomainError, models::UserSummary};
+use crate::{context::AppContext, queries::GetUsersQuery};
+
+pub async fn execute(
+    ctx: &AppContext,
+    _query: GetUsersQuery,
+) -> Result<Vec<UserSummary>, DomainError> {
+    ctx.user_repository.list_with_stats().await
+}