Scaffold BOS repo: dotfiles, ISO profile, and bos-settings GTK4 app

Implements all four components from the BOS spec:
- dotfiles/: default Hyprland, bread, breadbox, breadcrumbs configs
- iso/: archiso profiledef, package list, Calamares YAML modules, post-install.sh
- bos-settings/: Cargo workspace with GTK4 settings app (8 views: snapshots,
  packages, bread, breadbar, breadbox, breadcrumbs, breadpad, hyprland)

https://claude.ai/code/session_01WszGHvCmxgcyTwNSkfLF9P

bos-settings/src/ui/views/snapshots.rs

@@ -0,0 +1,167 @@
+use gtk4::prelude::*;
+use gtk4::{
+    Box as GBox, Button, Label, ListBox, ListBoxRow, MessageDialog, Orientation, ScrolledWindow,
+};
+use std::process::Command;
+
+struct SnapshotRow {
+    number: String,
+    date: String,
+    description: String,
+}
+
+fn list_snapshots() -> Vec<SnapshotRow> {
+    let Ok(output) = Command::new("snapper")
+        .args(["list", "--output-cols", "number,date,description"])
+        .output()
+    else {
+        return Vec::new();
+    };
+
+    let text = String::from_utf8_lossy(&output.stdout);
+    text.lines()
+        .skip(2) // header + separator
+        .filter_map(|line| {
+            let cols: Vec<&str> = line.splitn(3, '|').collect();
+            if cols.len() == 3 {
+                Some(SnapshotRow {
+                    number: cols[0].trim().to_string(),
+                    date: cols[1].trim().to_string(),
+                    description: cols[2].trim().to_string(),
+                })
+            } else {
+                None
+            }
+        })
+        .collect()
+}
+
+fn confirm_rollback(number: &str) {
+    let number = number.to_string();
+    let dialog = MessageDialog::new(
+        None::<&gtk4::Window>,
+        gtk4::DialogFlags::MODAL,
+        gtk4::MessageType::Question,
+        gtk4::ButtonsType::OkCancel,
+        &format!("Roll back to snapshot #{number}?\n\nReboot required to apply."),
+    );
+    dialog.connect_response(move |d, resp| {
+        if resp == gtk4::ResponseType::Ok {
+            let _ = Command::new("snapper")
+                .args(["rollback", &number])
+                .status();
+            let info = MessageDialog::new(
+                None::<&gtk4::Window>,
+                gtk4::DialogFlags::MODAL,
+                gtk4::MessageType::Info,
+                gtk4::ButtonsType::Ok,
+                "Rollback queued. Please reboot to apply.",
+            );
+            info.connect_response(|d, _| d.destroy());
+            info.present();
+        }
+        d.destroy();
+    });
+    dialog.present();
+}
+
+pub fn build() -> GBox {
+    let vbox = GBox::new(Orientation::Vertical, 0);
+    vbox.add_css_class("view-content");
+
+    let title = Label::new(Some("Snapshots"));
+    title.add_css_class("title");
+    title.set_xalign(0.0);
+    vbox.append(&title);
+
+    let subtitle =
+        Label::new(Some("System snapshots created by snap-pac on each pacman transaction."));
+    subtitle.set_xalign(0.0);
+    subtitle.set_margin_bottom(16);
+    vbox.append(&subtitle);
+
+    let list = ListBox::new();
+    list.set_selection_mode(gtk4::SelectionMode::Single);
+
+    let snapshots = list_snapshots();
+    if snapshots.is_empty() {
+        let row = ListBoxRow::new();
+        let lbl = Label::new(Some(
+            "No snapshots found (snapper may not be configured yet)",
+        ));
+        lbl.set_margin_top(8);
+        lbl.set_margin_bottom(8);
+        lbl.set_margin_start(8);
+        row.set_child(Some(&lbl));
+        list.append(&row);
+    } else {
+        for snap in &snapshots {
+            let row = ListBoxRow::new();
+            row.set_widget_name(&snap.number);
+
+            let hbox = GBox::new(Orientation::Horizontal, 16);
+            hbox.set_margin_top(6);
+            hbox.set_margin_bottom(6);
+            hbox.set_margin_start(8);
+            hbox.set_margin_end(8);
+
+            let num_lbl = Label::new(Some(&snap.number));
+            num_lbl.set_width_chars(4);
+            num_lbl.set_xalign(0.0);
+
+            let date_lbl = Label::new(Some(&snap.date));
+            date_lbl.set_width_chars(22);
+            date_lbl.set_xalign(0.0);
+
+            let desc_lbl = Label::new(Some(&snap.description));
+            desc_lbl.set_hexpand(true);
+            desc_lbl.set_xalign(0.0);
+
+            hbox.append(&num_lbl);
+            hbox.append(&date_lbl);
+            hbox.append(&desc_lbl);
+            row.set_child(Some(&hbox));
+            list.append(&row);
+        }
+    }
+
+    let scroll = ScrolledWindow::new();
+    scroll.set_vexpand(true);
+    scroll.set_child(Some(&list));
+    vbox.append(&scroll);
+
+    let btn_row = GBox::new(Orientation::Horizontal, 8);
+    btn_row.set_margin_top(12);
+
+    let rollback_btn = Button::with_label("Rollback to selected");
+    let delete_btn = Button::with_label("Delete selected");
+    delete_btn.add_css_class("destructive-action");
+
+    {
+        let list = list.clone();
+        rollback_btn.connect_clicked(move |_| {
+            let Some(row) = list.selected_row() else {
+                return;
+            };
+            let number = row.widget_name().to_string();
+            confirm_rollback(&number);
+        });
+    }
+
+    {
+        let list = list.clone();
+        delete_btn.connect_clicked(move |_| {
+            let Some(row) = list.selected_row() else {
+                return;
+            };
+            let number = row.widget_name().to_string();
+            let _ = Command::new("snapper").args(["delete", &number]).status();
+        });
+    }
+
+    btn_row.append(&rollback_btn);
+    btn_row.append(&delete_btn);
+    vbox.append(&btn_row);
+
+    vbox
+}