Feat: Replace bash scripts with a unified Go CLI

[Azzurriii]

Replaces the bash-based setup flow with a self-contained fystack CLI written in Go. The CLI covers the full stack lifecycle — guided setup, MPC node init, deploy, status, logs, image updates, and a new reset command — with no bash dependencies for day-to-day operations.
Changes:

• fystack setup — interactive guided setup (Bubble Tea TUI, Binance/CoinMarketCap choice, node gen, optional deploy)
• fystack init — MPC node config generation in Go via the mpcium-cli Docker image; replaces setup-nodes.sh
• fystack reset — removes all generated files to restore a clean clone state
• fystack deploy / status / restart / logs / check-updates / update — full Docker Compose lifecycle in Go