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/breadbar.rs

@@ -0,0 +1,58 @@
+use gtk4::prelude::*;
+use gtk4::{Box as GBox, Button, Label, Orientation, ScrolledWindow, TextView};
+use std::path::PathBuf;
+
+fn css_path() -> PathBuf {
+    let home = std::env::var("HOME").unwrap_or_else(|_| "/root".to_string());
+    PathBuf::from(home).join(".config/breadbar/style.css")
+}
+
+pub fn build() -> GBox {
+    let path = css_path();
+    let existing_css = std::fs::read_to_string(&path).unwrap_or_default();
+
+    let vbox = GBox::new(Orientation::Vertical, 12);
+    vbox.add_css_class("view-content");
+
+    let title = Label::new(Some("breadbar"));
+    title.add_css_class("title");
+    title.set_xalign(0.0);
+    vbox.append(&title);
+
+    let subtitle = Label::new(Some(
+        "CSS overrides for breadbar. Leave empty to use the default bread theme.",
+    ));
+    subtitle.set_xalign(0.0);
+    subtitle.set_margin_bottom(8);
+    subtitle.set_wrap(true);
+    vbox.append(&subtitle);
+
+    let buf = gtk4::TextBuffer::new(None);
+    buf.set_text(&existing_css);
+
+    let text_view = TextView::with_buffer(&buf);
+    text_view.set_monospace(true);
+
+    let scroll = ScrolledWindow::new();
+    scroll.set_vexpand(true);
+    scroll.set_child(Some(&text_view));
+    vbox.append(&scroll);
+
+    let save_btn = Button::with_label("Save");
+    save_btn.set_margin_top(12);
+    save_btn.set_halign(gtk4::Align::Start);
+    {
+        let path = path.clone();
+        save_btn.connect_clicked(move |_| {
+            let (start, end) = buf.bounds();
+            let text = buf.text(&start, &end, false);
+            if let Some(parent) = path.parent() {
+                let _ = std::fs::create_dir_all(parent);
+            }
+            let _ = std::fs::write(&path, text.as_str());
+        });
+    }
+    vbox.append(&save_btn);
+
+    vbox
+}