Mirrors tonight's breadbox migration (same shared crate, same duplicated
patterns):
- position.rs's raw socket1 client -> bread_utils::hypr (file removed
entirely, its logic now lives in the shared crate)
- toggle_or_continue's TOCTOU-prone PID-file dance -> bread_utils::singleton
- the layer-shell window setup, Up/Down visible-row navigation, and
click-outside-close gesture -> bread_utils::gtk_popup
- breadclip-core's data_dir(): replaced the buggy
`dirs::data_local_dir().unwrap_or_else(|| PathBuf::from("~/.local/share"))`
fallback (flagged but never fixed in tonight's earlier audit pass —
PathBuf never expands `~`) with bread_utils::xdg::data_dir, which
resolves a real $HOME before ever falling back.
Builds and tests clean across the whole breadclip workspace.
