File > New window (Ctrl/Cmd+N) starts another copy: `open -n` on a macOS bundle,
the executable elsewhere ($APPIMAGE on AppImage). Copies take a number from an OS
file lock in the data folder (instance-N.lock); the first behaves exactly as before.
Instance 2+ never rewrites the shared config.ini (own config-N.ini holds only window
size and controller choice), keeps game saves in saves/instance-N/ (first run reads
the shared save), uses imgui-N.ini, and hands the netplay address to the core through
VJ_NETLINK_HOST instead of the one shared vj_netlink.txt. Atomic writes now use a
per-process temp name. Settings > Input pins a window to one controller (or keyboard
only) and keeps reading it while another window has focus.
Refs #833
Refs #888
Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
