Add rename template presets and watermark color picker

- Rename step: quick-fill buttons for common patterns (Date+Name,
  EXIF Date+Name, Sequential, Dimensions, Camera+Date, Web-safe)
- Watermark step: color picker in advanced options using ColorDialogButton
- Add watermark_color field to JobConfig, wire through to core

pixstrip-gtk/src/app.rs

@@ -65,6 +65,7 @@ pub struct JobConfig {
     pub watermark_position: u32,
     pub watermark_opacity: f32,
     pub watermark_font_size: f32,
+    pub watermark_color: [u8; 4],
     pub watermark_use_image: bool,
     // Rename
     pub rename_enabled: bool,
@@ -312,6 +313,7 @@ fn build_ui(app: &adw::Application) {
             watermark_position: 8, // BottomRight
             watermark_opacity: 0.5,
             watermark_font_size: 24.0,
+            watermark_color: [255, 255, 255, 255],
             watermark_use_image: false,
             rename_enabled: if remember { sess_state.rename_enabled.unwrap_or(false) } else { false },
             rename_prefix: String::new(),
@@ -1495,7 +1497,7 @@ fn run_processing(_window: &adw::ApplicationWindow, ui: &WizardUi) {
                 position,
                 font_size: cfg.watermark_font_size,
                 opacity: cfg.watermark_opacity,
-                color: [255, 255, 255, 255],
+                color: cfg.watermark_color,
             });
         }
     }
@@ -2348,7 +2350,7 @@ fn build_preset_from_config(cfg: &JobConfig, name: &str) -> pixstrip_core::prese
                 position,
                 font_size: cfg.watermark_font_size,
                 opacity: cfg.watermark_opacity,
-                color: [255, 255, 255, 255],
+                color: cfg.watermark_color,
             })
         } else {
             None

pixstrip-gtk/src/steps/step_rename.rs

@@ -101,6 +101,44 @@ pub fn build_rename_page(state: &AppState) -> adw::NavigationPage {
         .text(&cfg.rename_template)
         .build();
 
+    // Preset template quick-fill buttons
+    let presets_flow = gtk::FlowBox::builder()
+        .selection_mode(gtk::SelectionMode::None)
+        .max_children_per_line(4)
+        .min_children_per_line(2)
+        .row_spacing(4)
+        .column_spacing(4)
+        .margin_top(4)
+        .margin_bottom(8)
+        .margin_start(12)
+        .margin_end(12)
+        .homogeneous(false)
+        .build();
+
+    let preset_templates = [
+        ("Date + Name", "{date}_{name}"),
+        ("EXIF Date + Name", "{exif_date}_{name}"),
+        ("Sequential", "{name}_{counter:4}"),
+        ("Dimensions", "{name}_{width}x{height}"),
+        ("Camera + Date", "{camera}_{exif_date}_{counter:3}"),
+        ("Web-safe", "{name}_web"),
+    ];
+
+    for (label, template) in &preset_templates {
+        let btn = gtk::Button::builder()
+            .label(*label)
+            .tooltip_text(*template)
+            .build();
+        btn.add_css_class("pill");
+
+        let tr = template_row.clone();
+        let tmpl = template.to_string();
+        btn.connect_clicked(move |_| {
+            tr.set_text(&tmpl);
+        });
+        presets_flow.append(&btn);
+    }
+
     let help_label = gtk::Label::builder()
         .label(
             "Available variables:\n\
@@ -145,6 +183,7 @@ pub fn build_rename_page(state: &AppState) -> adw::NavigationPage {
     regex_group.add(&replace_row);
 
     advanced_group.add(&template_row);
+    advanced_group.add(&presets_flow);
     advanced_group.add(&help_label);
     advanced_group.add(&case_row);
     content.append(&advanced_group);

pixstrip-gtk/src/steps/step_watermark.rs

@@ -315,6 +315,29 @@ pub fn build_watermark_page(state: &AppState) -> adw::NavigationPage {
         .expanded(state.detailed_mode)
         .build();
 
+    // Text color picker
+    let color_row = adw::ActionRow::builder()
+        .title("Text Color")
+        .subtitle("Color of the watermark text")
+        .build();
+
+    let initial_color = gtk::gdk::RGBA::new(
+        cfg.watermark_color[0] as f32 / 255.0,
+        cfg.watermark_color[1] as f32 / 255.0,
+        cfg.watermark_color[2] as f32 / 255.0,
+        cfg.watermark_color[3] as f32 / 255.0,
+    );
+    let color_dialog = gtk::ColorDialog::builder()
+        .with_alpha(true)
+        .title("Watermark Text Color")
+        .build();
+    let color_button = gtk::ColorDialogButton::builder()
+        .dialog(&color_dialog)
+        .rgba(&initial_color)
+        .valign(gtk::Align::Center)
+        .build();
+    color_row.add_suffix(&color_button);
+
     let opacity_row = adw::SpinRow::builder()
         .title("Opacity")
         .subtitle("0.0 (invisible) to 1.0 (fully opaque)")
@@ -347,6 +370,7 @@ pub fn build_watermark_page(state: &AppState) -> adw::NavigationPage {
         .adjustment(&gtk::Adjustment::new(20.0, 1.0, 100.0, 1.0, 5.0, 0.0))
         .build();
 
+    advanced_expander.add_row(&color_row);
     advanced_expander.add_row(&opacity_row);
     advanced_expander.add_row(&rotation_row);
     advanced_expander.add_row(&tiled_row);
@@ -424,6 +448,19 @@ pub fn build_watermark_page(state: &AppState) -> adw::NavigationPage {
             jc.borrow_mut().watermark_opacity = val;
         });
     }
+    // Wire color picker
+    {
+        let jc = state.job_config.clone();
+        color_button.connect_rgba_notify(move |btn| {
+            let c = btn.rgba();
+            jc.borrow_mut().watermark_color = [
+                (c.red() * 255.0) as u8,
+                (c.green() * 255.0) as u8,
+                (c.blue() * 255.0) as u8,
+                (c.alpha() * 255.0) as u8,
+            ];
+        });
+    }
     // Wire image chooser button
     {
         let jc = state.job_config.clone();