Add background update checks with configurable interval

src/ui/dashboard.rs

@@ -1,6 +1,8 @@
 use adw::prelude::*;
+use gtk::gio;
 use std::rc::Rc;
 
+use crate::config::APP_ID;
 use crate::core::database::Database;
 use crate::core::duplicates;
 use crate::core::fuse;
@@ -267,6 +269,32 @@ fn build_updates_summary_group(db: &Rc<Database>) -> adw::PreferencesGroup {
     updates_row.add_suffix(&updates_arrow);
     group.add(&updates_row);
 
+    // Last checked timestamp
+    let settings = gio::Settings::new(APP_ID);
+    let last_check = settings.string("last-update-check");
+    let last_label = if last_check.is_empty() {
+        "Never".to_string()
+    } else if let Ok(ts) = chrono::NaiveDateTime::parse_from_str(last_check.as_str(), "%Y-%m-%d %H:%M:%S") {
+        let now = chrono::Utc::now().naive_utc();
+        let elapsed = now.signed_duration_since(ts);
+        if elapsed.num_minutes() < 1 {
+            "Just now".to_string()
+        } else if elapsed.num_hours() < 1 {
+            format!("{}m ago", elapsed.num_minutes())
+        } else if elapsed.num_hours() < 24 {
+            format!("{}h ago", elapsed.num_hours())
+        } else {
+            format!("{}d ago", elapsed.num_days())
+        }
+    } else {
+        "Unknown".to_string()
+    };
+    let last_row = adw::ActionRow::builder()
+        .title("Last checked")
+        .subtitle(&last_label)
+        .build();
+    group.add(&last_row);
+
     group
 }