Add processing, results, and settings UI screens

Processing screen with progress bar, activity log, and pause/cancel.
Results screen with stats summary, error section, and action buttons.
Settings dialog with General, Processing, Accessibility, Notifications.

pixstrip-gtk/src/settings.rs

@@ -0,0 +1,161 @@
+use adw::prelude::*;
+
+#[allow(dead_code)]
+pub fn build_settings_dialog() -> adw::PreferencesDialog {
+    let dialog = adw::PreferencesDialog::builder()
+        .title("Settings")
+        .build();
+
+    // General page
+    let general_page = adw::PreferencesPage::builder()
+        .title("General")
+        .icon_name("preferences-system-symbolic")
+        .build();
+
+    let output_group = adw::PreferencesGroup::builder()
+        .title("Output")
+        .build();
+
+    let subfolder_row = adw::EntryRow::builder()
+        .title("Default output subfolder")
+        .text("processed")
+        .build();
+
+    let overwrite_row = adw::ComboRow::builder()
+        .title("Default overwrite behavior")
+        .subtitle("What to do when output files already exist")
+        .build();
+    let overwrite_model = gtk::StringList::new(&[
+        "Ask before overwriting",
+        "Auto-rename with suffix",
+        "Always overwrite",
+        "Skip existing files",
+    ]);
+    overwrite_row.set_model(Some(&overwrite_model));
+
+    let remember_row = adw::SwitchRow::builder()
+        .title("Remember last-used settings")
+        .subtitle("Restore wizard state on next launch")
+        .active(true)
+        .build();
+
+    output_group.add(&subfolder_row);
+    output_group.add(&overwrite_row);
+    output_group.add(&remember_row);
+    general_page.add(&output_group);
+
+    let ui_group = adw::PreferencesGroup::builder()
+        .title("Interface")
+        .build();
+
+    let skill_row = adw::ComboRow::builder()
+        .title("Detail level")
+        .subtitle("Controls how many options are visible by default")
+        .build();
+    let skill_model = gtk::StringList::new(&["Simple", "Detailed"]);
+    skill_row.set_model(Some(&skill_model));
+
+    ui_group.add(&skill_row);
+    general_page.add(&ui_group);
+    dialog.add(&general_page);
+
+    // Processing page
+    let processing_page = adw::PreferencesPage::builder()
+        .title("Processing")
+        .icon_name("system-run-symbolic")
+        .build();
+
+    let threads_group = adw::PreferencesGroup::builder()
+        .title("Performance")
+        .build();
+
+    let threads_row = adw::ComboRow::builder()
+        .title("Processing threads")
+        .subtitle("Auto uses all available CPU cores")
+        .build();
+    let threads_model = gtk::StringList::new(&["Auto", "1", "2", "4", "8"]);
+    threads_row.set_model(Some(&threads_model));
+
+    let error_row = adw::ComboRow::builder()
+        .title("On error")
+        .subtitle("What to do when an image fails to process")
+        .build();
+    let error_model = gtk::StringList::new(&["Skip and continue", "Pause on error"]);
+    error_row.set_model(Some(&error_model));
+
+    threads_group.add(&threads_row);
+    threads_group.add(&error_row);
+    processing_page.add(&threads_group);
+    dialog.add(&processing_page);
+
+    // Accessibility page
+    let a11y_page = adw::PreferencesPage::builder()
+        .title("Accessibility")
+        .icon_name("preferences-desktop-accessibility-symbolic")
+        .build();
+
+    let a11y_group = adw::PreferencesGroup::builder()
+        .title("Visual Preferences")
+        .description("Override system settings for this app only")
+        .build();
+
+    let contrast_row = adw::SwitchRow::builder()
+        .title("High contrast")
+        .subtitle("Increase visual contrast throughout the app")
+        .active(false)
+        .build();
+
+    let large_text_row = adw::SwitchRow::builder()
+        .title("Large text")
+        .subtitle("Increase text size throughout the app")
+        .active(false)
+        .build();
+
+    let motion_row = adw::SwitchRow::builder()
+        .title("Reduced motion")
+        .subtitle("Minimize animations and transitions")
+        .active(false)
+        .build();
+
+    a11y_group.add(&contrast_row);
+    a11y_group.add(&large_text_row);
+    a11y_group.add(&motion_row);
+    a11y_page.add(&a11y_group);
+    dialog.add(&a11y_page);
+
+    // Notifications page
+    let notify_page = adw::PreferencesPage::builder()
+        .title("Notifications")
+        .icon_name("preferences-system-notifications-symbolic")
+        .build();
+
+    let notify_group = adw::PreferencesGroup::builder()
+        .title("Completion")
+        .build();
+
+    let desktop_notify_row = adw::SwitchRow::builder()
+        .title("Desktop notification")
+        .subtitle("Show notification when processing completes")
+        .active(true)
+        .build();
+
+    let sound_row = adw::SwitchRow::builder()
+        .title("Completion sound")
+        .subtitle("Play a sound when processing completes")
+        .active(false)
+        .build();
+
+    let auto_open_row = adw::SwitchRow::builder()
+        .title("Auto-open output folder")
+        .subtitle("Open the output folder in file manager when done")
+        .active(false)
+        .build();
+
+    notify_group.add(&desktop_notify_row);
+    notify_group.add(&sound_row);
+    notify_group.add(&auto_open_row);
+    notify_page.add(&notify_group);
+    dialog.add(&notify_page);
+
+    dialog
+}