feat: add AdaptixCLI - CLI tool for server interaction

[wxfbot03-lang]

Summary

Adds a Go-based CLI tool (AdaptixCLI/) for interacting with the AdaptixC2 server.

Features

• agent list — show all agents, with --online filter and --json output
• agent info <id> — detailed agent information
• agent exec <id> <command> — single command execution with real-time output
• agent terminal <id> — raw-mode remote shell (fully interactive, Ctrl+C/D/Z passthrough)
• listener list/start/stop — listener management
• download list/get — file download management

Design

• Standalone Go module (not in go.workspace), uses stdlib + gorilla/websocket + goccy/go-yaml + golang.org/x/term
• Config stored in ~/.adaptix/adaptix-cil.yaml
• Build via make cli or make install-cli
• Connects via REST + WebSocket (JWT auth -> OTP -> sync protocol)
• Terminal mode uses secondary WebSocket channel for real-time I/O

[CleverNamesTaken]

I started playing with this a bit because I really want a CLI.

I noticed a few things:

1. CLI is often misspelled as CIL
2. The cli is non-interactive. A REPL-like shell would be really awesome.

@RalfHacker is not likely going to action this PR per #329, but I'd be happy to collaborate with you to fix this up a bit whenever v2.0 comes out.