feat(admin): overview dashboard sections + system temperature/load sensors (0.85.0) (#11)

backend/src/repo/user.rs

@@ -1,11 +1,31 @@
 //! User persistence.
 
+use chrono::{DateTime, Utc};
 use sqlx::PgPool;
 use uuid::Uuid;
 
 use crate::domain::User;
 use crate::error::{AppError, AppResult};
 
+/// `(total, admins)` user counts for the admin overview dashboard.
+pub async fn counts(pool: &PgPool) -> AppResult<(i64, i64)> {
+    let row: (i64, i64) = sqlx::query_as(
+        "SELECT COUNT(*)::bigint, COUNT(*) FILTER (WHERE is_admin)::bigint FROM users",
+    )
+    .fetch_one(pool)
+    .await?;
+    Ok(row)
+}
+
+/// Most recently created user (username, created_at), if any exist.
+pub async fn newest(pool: &PgPool) -> AppResult<Option<(String, DateTime<Utc>)>> {
+    let row: Option<(String, DateTime<Utc>)> =
+        sqlx::query_as("SELECT username, created_at FROM users ORDER BY created_at DESC LIMIT 1")
+            .fetch_optional(pool)
+            .await?;
+    Ok(row)
+}
+
 pub async fn create(pool: &PgPool, username: &str, password_hash: &str) -> AppResult<User> {
     let result = sqlx::query_as::<_, User>(
         r#"