Wire welcome dialog with navigation and first-run detection

- Welcome dialog buttons navigate between pages
- Done button closes dialog and marks first_run_complete
- Show welcome dialog on first launch only
- Add first_run_complete field to AppConfig with serde(default)

pixstrip-gtk/src/welcome.rs

@@ -1,7 +1,26 @@
 use adw::prelude::*;
 
-#[allow(dead_code)]
-pub fn build_welcome_dialog() -> adw::Dialog {
+pub fn show_welcome_if_first_launch(window: &adw::ApplicationWindow) {
+    let config = pixstrip_core::storage::ConfigStore::new();
+    if let Ok(cfg) = config.load()
+        && cfg.first_run_complete
+    {
+        return;
+    }
+
+    let dialog = build_welcome_dialog();
+    let win = window.clone();
+    dialog.connect_closed(move |_| {
+        let config = pixstrip_core::storage::ConfigStore::new();
+        if let Ok(mut cfg) = config.load() {
+            cfg.first_run_complete = true;
+            let _ = config.save(&cfg);
+        }
+    });
+    dialog.present(Some(&win));
+}
+
+fn build_welcome_dialog() -> adw::Dialog {
     let dialog = adw::Dialog::builder()
         .title("Welcome to Pixstrip")
         .content_width(500)
@@ -10,23 +29,20 @@ pub fn build_welcome_dialog() -> adw::Dialog {
 
     let nav_view = adw::NavigationView::new();
 
-    // Page 1: Welcome
-    let welcome_page = build_welcome_page();
+    let welcome_page = build_welcome_page(&nav_view);
     nav_view.add(&welcome_page);
 
-    // Page 2: Skill level
-    let skill_page = build_skill_page();
+    let skill_page = build_skill_page(&nav_view);
     nav_view.add(&skill_page);
 
-    // Page 3: Output defaults
-    let output_page = build_output_page();
+    let output_page = build_output_page(&dialog);
     nav_view.add(&output_page);
 
     dialog.set_child(Some(&nav_view));
     dialog
 }
 
-fn build_welcome_page() -> adw::NavigationPage {
+fn build_welcome_page(nav_view: &adw::NavigationView) -> adw::NavigationPage {
     let content = gtk::Box::builder()
         .orientation(gtk::Orientation::Vertical)
         .spacing(12)
@@ -50,6 +66,11 @@ fn build_welcome_page() -> adw::NavigationPage {
     next_button.add_css_class("suggested-action");
     next_button.add_css_class("pill");
 
+    let nav = nav_view.clone();
+    next_button.connect_clicked(move |_| {
+        nav.push_by_tag("skill-level");
+    });
+
     content.append(&status);
     content.append(&next_button);
 
@@ -60,7 +81,7 @@ fn build_welcome_page() -> adw::NavigationPage {
         .build()
 }
 
-fn build_skill_page() -> adw::NavigationPage {
+fn build_skill_page(nav_view: &adw::NavigationView) -> adw::NavigationPage {
     let content = gtk::Box::builder()
         .orientation(gtk::Orientation::Vertical)
         .spacing(12)
@@ -116,6 +137,11 @@ fn build_skill_page() -> adw::NavigationPage {
     next_button.add_css_class("suggested-action");
     next_button.add_css_class("pill");
 
+    let nav = nav_view.clone();
+    next_button.connect_clicked(move |_| {
+        nav.push_by_tag("output-location");
+    });
+
     content.append(&title);
     content.append(&subtitle);
     content.append(&group);
@@ -128,7 +154,7 @@ fn build_skill_page() -> adw::NavigationPage {
         .build()
 }
 
-fn build_output_page() -> adw::NavigationPage {
+fn build_output_page(dialog: &adw::Dialog) -> adw::NavigationPage {
     let content = gtk::Box::builder()
         .orientation(gtk::Orientation::Vertical)
         .spacing(12)
@@ -184,6 +210,11 @@ fn build_output_page() -> adw::NavigationPage {
     done_button.add_css_class("suggested-action");
     done_button.add_css_class("pill");
 
+    let dlg = dialog.clone();
+    done_button.connect_clicked(move |_| {
+        dlg.close();
+    });
+
     content.append(&title);
     content.append(&subtitle);
     content.append(&group);