perf: async fprintd initialization for instant window display

Move all fprintd D-Bus calls (init, availability check, claim, verify)
from synchronous to async using gio futures. Windows now appear
immediately without waiting for D-Bus — fingerprint label fades in
once fprintd is ready. Single shared FingerprintListener across all
monitors instead of one per monitor.

src/main.rs

@@ -13,9 +13,12 @@ use gdk4 as gdk;
 use gtk4::prelude::*;
 use gtk4::{self as gtk, gio};
 use gtk4_session_lock;
+use std::cell::RefCell;
 use std::path::PathBuf;
 use std::rc::Rc;
 
+use crate::fingerprint::FingerprintListener;
+
 fn load_css(display: &gdk::Display) {
     let css_provider = gtk::CssProvider::new();
     css_provider.load_from_resource("/dev/moonarch/moonlock/style.css");
@@ -75,27 +78,67 @@ fn activate_with_session_lock(
         app_clone.quit();
     });
 
+    // Create all monitor windows immediately — no D-Bus calls here
+    let mut all_handles = Vec::new();
     let mut created_any = false;
     for i in 0..monitors.n_items() {
         if let Some(monitor) = monitors
             .item(i)
             .and_then(|obj| obj.downcast::<gdk::Monitor>().ok())
         {
-            let window = lockscreen::create_lockscreen_window(
+            let handles = lockscreen::create_lockscreen_window(
                 bg_path,
                 config,
                 app,
                 unlock_callback.clone(),
             );
-            lock.assign_window_to_monitor(&window, &monitor);
-            window.present();
+            lock.assign_window_to_monitor(&handles.window, &monitor);
+            handles.window.present();
+            all_handles.push(handles);
             created_any = true;
         }
     }
 
     if !created_any {
         log::error!("No lockscreen windows created — screen stays locked (compositor policy)");
+        return;
     }
+
+    // Async fprintd initialization — runs after windows are visible
+    if config.fingerprint_enabled {
+        init_fingerprint_async(all_handles);
+    }
+}
+
+/// Initialize fprintd asynchronously after windows are visible.
+/// Uses a single FingerprintListener shared across all monitors —
+/// only the first monitor's handles get the fingerprint UI wired up.
+fn init_fingerprint_async(all_handles: Vec<lockscreen::LockscreenHandles>) {
+    glib::spawn_future_local(async move {
+        let mut listener = FingerprintListener::new();
+        listener.init_async().await;
+
+        // Use the first monitor's username to check enrollment
+        let username = &all_handles[0].username;
+        if username.is_empty() {
+            return;
+        }
+
+        if !listener.is_available_async(username).await {
+            log::debug!("fprintd not available or no enrolled fingers");
+            return;
+        }
+
+        let fp_rc = Rc::new(RefCell::new(listener));
+
+        // Show fingerprint label on all monitors
+        for handles in &all_handles {
+            lockscreen::show_fingerprint_label(handles, &fp_rc);
+        }
+
+        // Start verification listener on the first monitor only
+        lockscreen::start_fingerprint(&all_handles[0], &fp_rc);
+    });
 }
 
 #[cfg(debug_assertions)]
@@ -109,14 +152,19 @@ fn activate_without_lock(
         app_clone.quit();
     });
 
-    let window = lockscreen::create_lockscreen_window(
+    let handles = lockscreen::create_lockscreen_window(
         bg_path,
         config,
         app,
         unlock_callback,
     );
-    window.set_default_size(800, 600);
-    window.present();
+    handles.window.set_default_size(800, 600);
+    handles.window.present();
+
+    // Async fprintd initialization for development mode
+    if config.fingerprint_enabled {
+        init_fingerprint_async(vec![handles]);
+    }
 }
 
 fn setup_logging() {