Add font family selector for watermark text

pixstrip-gtk/src/steps/step_watermark.rs

@@ -61,7 +61,31 @@ pub fn build_watermark_page(state: &AppState) -> adw::NavigationPage {
         .adjustment(&gtk::Adjustment::new(cfg.watermark_font_size as f64, 8.0, 200.0, 1.0, 10.0, 0.0))
         .build();
 
+    // Font family picker
+    let font_row = adw::ActionRow::builder()
+        .title("Font Family")
+        .subtitle("Choose a typeface for the watermark text")
+        .build();
+
+    let font_dialog = gtk::FontDialog::builder()
+        .title("Choose Watermark Font")
+        .modal(true)
+        .build();
+    let font_button = gtk::FontDialogButton::builder()
+        .dialog(&font_dialog)
+        .valign(gtk::Align::Center)
+        .build();
+
+    // Set initial font if one was previously selected
+    if !cfg.watermark_font_family.is_empty() {
+        let desc = gtk::pango::FontDescription::from_string(&cfg.watermark_font_family);
+        font_button.set_font_desc(&desc);
+    }
+
+    font_row.add_suffix(&font_button);
+
     text_group.add(&text_row);
+    text_group.add(&font_row);
     text_group.add(&font_size_row);
     content.append(&text_group);
 
@@ -415,6 +439,16 @@ pub fn build_watermark_page(state: &AppState) -> adw::NavigationPage {
             jc.borrow_mut().watermark_font_size = row.value() as f32;
         });
     }
+    // Wire font family picker
+    {
+        let jc = state.job_config.clone();
+        font_button.connect_font_desc_notify(move |btn| {
+            let desc = btn.font_desc();
+            if let Some(family) = desc.family() {
+                jc.borrow_mut().watermark_font_family = family.to_string();
+            }
+        });
+    }
     // Wire position grid buttons
     for (i, btn) in buttons.iter().enumerate() {
         let jc = state.job_config.clone();