v2.0.0 — GUI Edition

• 🖥️ Desktop GUI (Tkinter, no extra GUI dependency) — a single,
  resizable window split into two columns: Process (settings, controls,
  progress bar, log) on the left and a live-updating Results table on
  the right.
• 🌍 Country flags — each live proxy is geolocated and shown with its
  flag emoji, IP, port and HTTPS support.
• 🚀 Multithreaded checking (configurable thread count, default 100).
• 🔒 Real HTTPS detection — every proxy is tested against both a plain
  HTTP endpoint and an HTTPS endpoint, so "HTTPS" in the results means the
  proxy can actually tunnel HTTPS traffic, not just that it responded.
• 📚 Multiple proxy sources merged and deduplicated, so one dead source
  doesn't stop a run.
• ⏹️ Start/Stop control — cancel a run in progress at any time.
• 💾 CSV export, both automatically after each run (live_proxies.csv)
  and on demand from the Results window ("Export CSV" button).
• 🧵 Fully non-blocking UI — networking happens on background threads and
  reports progress through a thread-safe queue.