bos-settings 0.4.1: fix broken panels, add breadsearch view

- breadbox panel edited [[contexts]] but breadbox reads [[context]]
  (serde rename mismatch) — panel was always empty and Save appended
  a dead array.
- Packages panel parsed installed.json as a flat map instead of
  unwrapping {"packages": {...}} — always showed one bogus row.
- load_doc silently produced an empty document on any parse error,
  so the next Save could clobber a config file with a syntax typo;
  now backs it up first.
- Hyprland panel opened hyprland.conf/keybinds.conf (BOS ships
  hyprland.lua) via $EDITOR with no terminal (dead click for any TUI
  editor) and defaulted to foot (BOS ships kitty). Now opens
  hyprland.lua and a keybinds cheat sheet via kitty -e $EDITOR.
- New breadsearch view: power (enabled/run-on-battery), compute
  backend (cpu/npu/rocm), index/search settings.

bos-settings/src/ui/window.rs

@@ -32,6 +32,7 @@ pub fn build_ui(app: &Application) {
     stack.add_named(&views::breadbox::build(), Some("breadbox"));
     stack.add_named(&views::breadcrumbs::build(), Some("breadcrumbs"));
     stack.add_named(&views::breadpad::build(), Some("breadpad"));
+    stack.add_named(&views::breadsearch::build(), Some("breadsearch"));
     stack.add_named(&views::hyprland::build(), Some("hyprland"));
 
     // Default to snapshots view