feat: Allow running `atuin search -i` as subcommand (#3208)

Allow `atuin search -i` to work in command substitution contexts like
`VAR=$(atuin search -i)`.

Previously this would fail with "The cursor position could not be read
within a normal duration" because stdout was captured by the subshell,
preventing terminal queries from working.

Changes:

- When stdout isn't a terminal, fall back to /dev/tty for TUI rendering
(Unix only)
- Force fullscreen mode in this case (inline mode requires cursor
position queries that don't work with captured stdout)
- Write the selected command to stdout (instead of stderr) when stdout
is captured, so it gets assigned to the variable

Fixes #3207

0 files changed, 0 insertions, 0 deletions