install_dependencies_apt.py previously reported only which packages
failed, not why - the actual apt/pip error was discarded (apt) or
could scroll out of the on_error log tail (pip), leaving "Step 7:
Install web interface dependencies (line 915)" as the only visible
detail.
Capture command output for each install attempt and print a compact
DEPENDENCY INSTALLATION FAILURES summary with the last lines of error
output per package. Also run the installer with `python3 -u` for
real-time, correctly-ordered logging, and widen the on_error tail from
50 to 100 lines so the summary isn't cut off.
set +e alone doesn't suppress bash's ERR trap, so any non-zero exit from
first_time_install.sh inside the one-shot installer immediately triggered
the outer on_error handler with a generic "Main installation, line 370"
message — before the script could report the real exit code or point to
logs/. Suspend the trap for that block so the existing if/else handling
runs instead.
Chuck