Migrate config load/save to bread_utils::tomlcfg; timeout-guard hyprctl calls

config.rs's config_dir/load_doc/save_doc/atomic_write were a byte-for-byte
copy of bos-settings/src/config/mod.rs's versions (own doc comment said as
much) introduced in the same fix pass that added them there — now both
delegate to bread_utils::tomlcfg/bread_utils::atomic instead of each
carrying their own copy (path dependency for now, see the TODO in
Cargo.toml).

Also: services/hyprland.rs::query_json used a bare Command::output() with
no timeout, so an unresponsive hyprctl (Hyprland wedged/reloading) could
block clients()/monitors()/layers() indefinitely — switched to
bread_utils::proc::run_json with a 3s cap.

Builds clean; all 8 existing tests pass.

Cargo.lock

@@ -37,12 +37,23 @@ dependencies = [
  "serde_json",
 ]
 
+[[package]]
+name = "bread-utils"
+version = "0.2.3"
+dependencies = [
+ "dirs",
+ "serde",
+ "serde_json",
+ "toml_edit 0.22.27",
+]
+
 [[package]]
 name = "breadhelp"
 version = "0.2.1"
 dependencies = [
  "async-channel",
  "bread-theme",
+ "bread-utils",
  "gdk4",
  "glib",
  "gtk4",