Fish shell does not support "&&" and "||" operators like
POSIX-compatible shells. Instead, it uses a different syntax structure
based on begin/end and if/else.
This caused existing lazygit nvim-remote integration templates to break
when fish was the user's default shell.
This commit adds explicit fish shell detection using the FISH_VERSION
environment variable, and provides fish-compatible templates that
correctly handle launching Neovim or sending remote commands via $NVIM.
Fixes behavior where edits would not open in a new Neovim tab or line
navigation would fail when $NVIM was set.
Ensures smoother editing experience for users running fish shell
(supported since Nov 2012 with FISH_VERSION).
