caesar mutli-platform

Added

• Platform detection logic for Debian-based systems and Termux.
• Dynamic executable naming (caesar_executable for Debian, termux_executable for Termux).

Changed

• BREAKING: Migrated installation paths from system-wide directories (/opt, /sbin) to user-local paths (~/.local/share, ~/.local/bin).
• Installation script now avoids sudo by default for improved security and accessibility.

Fixed

• Backward compatibility with existing installations during path transitions.
• Permission handling for non-root users.