Add FUSE fix wizard with pkexec installation

Dashboard shows a banner when FUSE is not functional. The wizard
detects the distro, shows the install command, and runs it via pkexec.
Verifies FUSE status after installation completes.

src/ui/dashboard.rs

@@ -26,6 +26,18 @@ pub fn build_dashboard_page(db: &Rc<Database>) -> adw::NavigationPage {
         .margin_end(18)
         .build();
 
+    // FUSE warning banner if not functional
+    let fuse_info = fuse::detect_system_fuse();
+    if !fuse_info.status.is_functional() {
+        let banner = adw::Banner::builder()
+            .title("FUSE is not working - some AppImages may not launch")
+            .button_label("Fix Now")
+            .revealed(true)
+            .build();
+        banner.set_action_name(Some("win.fix-fuse"));
+        content.append(&banner);
+    }
+
     // Section 1: System Status
     content.append(&build_system_status_group());
 

src/ui/fuse_wizard.rs

@@ -0,0 +1,177 @@
+use adw::prelude::*;
+use gtk::gio;
+
+use crate::core::fuse;
+use crate::i18n::i18n;
+
+/// Show a FUSE installation wizard dialog.
+pub fn show_fuse_wizard(parent: &impl IsA<gtk::Widget>) {
+    let system_info = fuse::detect_system_fuse();
+    if system_info.status.is_functional() {
+        let dialog = adw::AlertDialog::builder()
+            .heading(&i18n("FUSE is working"))
+            .body(&i18n("libfuse2 is installed and functional. No action needed."))
+            .build();
+        dialog.add_response("ok", &i18n("OK"));
+        dialog.present(Some(parent));
+        return;
+    }
+
+    let install_cmd = match fuse::get_fuse_install_command() {
+        Some(cmd) => cmd,
+        None => {
+            let dialog = adw::AlertDialog::builder()
+                .heading(&i18n("Unknown distribution"))
+                .body(&i18n(
+                    "Could not detect your Linux distribution. Please install libfuse2 manually using your package manager.",
+                ))
+                .build();
+            dialog.add_response("ok", &i18n("OK"));
+            dialog.present(Some(parent));
+            return;
+        }
+    };
+
+    let dialog = adw::Dialog::builder()
+        .title(&i18n("Install FUSE"))
+        .content_width(480)
+        .content_height(350)
+        .build();
+
+    let toolbar = adw::ToolbarView::new();
+    let header = adw::HeaderBar::new();
+    toolbar.add_top_bar(&header);
+
+    let content = gtk::Box::builder()
+        .orientation(gtk::Orientation::Vertical)
+        .spacing(18)
+        .margin_start(24)
+        .margin_end(24)
+        .margin_top(18)
+        .margin_bottom(18)
+        .build();
+
+    let title = gtk::Label::builder()
+        .label(&i18n("FUSE is required"))
+        .xalign(0.0)
+        .build();
+    title.add_css_class("title-3");
+    content.append(&title);
+
+    let explanation = gtk::Label::builder()
+        .label(&i18n(
+            "Most AppImages require libfuse2 to mount and run. \
+             Without it, apps will use a slower extract-and-run fallback or may not launch at all.",
+        ))
+        .wrap(true)
+        .xalign(0.0)
+        .build();
+    content.append(&explanation);
+
+    // Show the detected issue
+    let issue_label = gtk::Label::builder()
+        .label(&format!("Status: {}", system_info.status.label()))
+        .xalign(0.0)
+        .build();
+    issue_label.add_css_class("heading");
+    content.append(&issue_label);
+
+    // Show the command
+    let cmd_label = gtk::Label::builder()
+        .label(&format!("Command: {}", install_cmd))
+        .xalign(0.0)
+        .selectable(true)
+        .build();
+    cmd_label.add_css_class("monospace");
+    content.append(&cmd_label);
+
+    // Status label for result
+    let status_label = gtk::Label::builder()
+        .xalign(0.0)
+        .wrap(true)
+        .visible(false)
+        .build();
+    content.append(&status_label);
+
+    // Install button
+    let button_box = gtk::Box::builder()
+        .orientation(gtk::Orientation::Horizontal)
+        .spacing(12)
+        .halign(gtk::Align::End)
+        .margin_top(12)
+        .build();
+
+    let install_btn = gtk::Button::builder()
+        .label(&i18n("Install via pkexec"))
+        .build();
+    install_btn.add_css_class("suggested-action");
+    install_btn.add_css_class("pill");
+
+    button_box.append(&install_btn);
+    content.append(&button_box);
+
+    toolbar.set_content(Some(&content));
+    dialog.set_child(Some(&toolbar));
+
+    let cmd = install_cmd.clone();
+    let status_ref = status_label.clone();
+    let btn_ref = install_btn.clone();
+    install_btn.connect_clicked(move |_| {
+        btn_ref.set_sensitive(false);
+        status_ref.set_visible(true);
+        status_ref.set_label(&i18n("Running installation..."));
+
+        let cmd = cmd.clone();
+        let status = status_ref.clone();
+        let btn = btn_ref.clone();
+        glib::spawn_future_local(async move {
+            let result = gio::spawn_blocking(move || {
+                // Split command into program and args
+                let parts: Vec<&str> = cmd.split_whitespace().collect();
+                if parts.is_empty() {
+                    return Err("Empty command".to_string());
+                }
+                let program = parts[0];
+                let args = &parts[1..];
+
+                std::process::Command::new("pkexec")
+                    .arg(program)
+                    .args(args)
+                    .status()
+                    .map_err(|e| format!("Failed to run pkexec: {}", e))
+            })
+            .await;
+
+            match result {
+                Ok(Ok(exit)) if exit.success() => {
+                    // Verify FUSE is now working
+                    let fuse_info = fuse::detect_system_fuse();
+                    if fuse_info.status.is_functional() {
+                        status.set_label(&i18n("FUSE installed successfully! AppImages should now mount natively."));
+                        status.add_css_class("success");
+                    } else {
+                        status.set_label(&i18n("Installation completed but FUSE still not detected. A reboot may be required."));
+                        status.add_css_class("warning");
+                    }
+                }
+                Ok(Ok(_)) => {
+                    status.set_label(&i18n("Installation was cancelled or failed."));
+                    status.add_css_class("error");
+                    btn.set_sensitive(true);
+                }
+                Ok(Err(e)) => {
+                    status.set_label(&format!("Error: {}", e));
+                    status.add_css_class("error");
+                    btn.set_sensitive(true);
+                }
+                Err(_) => {
+                    status.set_label(&i18n("Task failed unexpectedly."));
+                    status.add_css_class("error");
+                    btn.set_sensitive(true);
+                }
+            }
+        });
+    });
+
+    dialog.present(Some(parent));
+}

src/ui/mod.rs

@@ -5,6 +5,7 @@ pub mod dashboard;
 pub mod detail_view;
 pub mod drop_dialog;
 pub mod duplicate_dialog;
+pub mod fuse_wizard;
 pub mod integration_dialog;
 pub mod library_view;
 pub mod preferences;