install_binary() now:
1. Automatically picks best location per platform:
- macOS: ~/.cargo/bin/ (no sudo, in PATH for Rust users)
- Linux: ~/.cargo/bin/ → /usr/local/bin → ~/.local/bin/
- Windows: /usr/local/bin (Git Bash/MSYS2)
2. Detects if old binary exists at a different PATH location
and warns the user: 'There is ANOTHER gyandoot at ...'
3. Verifies 'command -v gyandoot' resolves correctly after install
4. Shows shell profile instructions if PATH needs updating
Previous issue: always installed to /usr/local/bin with sudo,
overwriting the old binary from install.sh but not warning if
another copy existed elsewhere in PATH.