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
 }
 

src/ui/preferences.rs

@@ -235,6 +235,25 @@ fn build_behavior_page(settings: &gio::Settings) -> adw::PreferencesPage {
     });
     automation_group.add(&auto_update_row);
 
+    let interval_row = adw::SpinRow::builder()
+        .title(&i18n("Update check interval"))
+        .subtitle(&i18n("Hours between automatic update checks"))
+        .build();
+    let interval_adj = gtk::Adjustment::new(
+        settings.int("update-check-interval-hours") as f64,
+        1.0,
+        168.0,
+        1.0,
+        6.0,
+        0.0,
+    );
+    interval_row.set_adjustment(Some(&interval_adj));
+    let settings_interval = settings.clone();
+    interval_row.connect_value_notify(move |row| {
+        settings_interval.set_int("update-check-interval-hours", row.value() as i32).ok();
+    });
+    automation_group.add(&interval_row);
+
     let auto_integrate_row = adw::SwitchRow::builder()
         .title(&i18n("Auto-integrate new AppImages"))
         .subtitle(&i18n("Automatically add newly discovered AppImages to the desktop menu"))