1. Move controller construction before _setup_signals/_setup_ui —
signals reference controller methods at connect time.
2. Restore _post_id_from_library_path, _set_library_info,
_on_library_selected, _on_library_activated — accidentally deleted
in the commit 4/6 line-range removals (they lived adjacent to
methods being extracted and got caught in the sweep).
behavior change: none (restores lost code, fixes startup crash)
pax
f9977b61e6