v0.3.0 — DFS Pipeline, Discovery, Throughput, SOCKS5 Auth

What's New (from v0.2.2.1)

• DFS Pipeline (--dfs) — opt-in instant results mode; BFS remains default
• Neighbor Discovery (--discover) — auto-scan /24 subnets with --discover-max cap
• Throughput Test (--throughput) — payload transfer through tunnel
• SOCKS5 Auth (--socks-user, --socks-pass) — RFC 1929 username/password
• SSH Probe (--connect-addr host:22) — SSH banner verification
• TUI Overhaul — scrollable live results, step breakdown, all new config fields
• Live File Output — _ips.txt written in real-time during DFS scan

All review issues from PR SamNet-dev#7 addressed: goroutine leak fixed, DFS opt-in (not default), discovery capped, throughput threshold fixed, file overwrite fixed.