Initialize an error buffer and collect yt-dlp "ERROR:" output lines during direct command runs. When the process exits non‑zero, emit a more informative error using the last two captured error lines (falling back to the generic return-code message if none were captured). Also ensure the buffer is present before appending and keep the existing delay/cleanup flow.
Renamed 'src/core' to 'ytsage/core' and updated all internal imports to use relative paths. This improves package structure and ensures correct module resolution after the directory move.
oop7