docs: expand README with project overview

README.md

@@ -1,3 +1,20 @@
-# elmprodvpn
+# elmprodvpn (Selective VPN Dashboard)
 
-Devlop app selective vpn
+Local Linux toolset (Go API + Qt GUI) to manage selective VPN routing and DNS wildcarding for AdGuard VPN / SmartDNS.
+
+Key features:
+- Selective routes via nftables sets (`agvpn4` / `agvpn_dyn4`) + policy routing table (`agvpn`).
+- DNS upstream management (default + meta) and optional SmartDNS wildcard list.
+- Traffic modes: Selective (fwmark `0x66`), Full tunnel, Direct.
+- Auto-local bypass to keep LAN/docker reachable in Full tunnel.
+- Policy overrides: force VPN/Direct by source subnet, UID, or systemd cgroup.
+- Runtime per-app routing: launch an app in a `systemd --user` scope and apply a temporary cgroup-based mark.
+
+Repo layout:
+- `selective-vpn-api/` - Go backend API (localhost, default `127.0.0.1:8080`).
+- `selective-vpn-gui/` - PySide6 GUI (`vpn_dashboard_qt.py`).
+
+Requirements (high level):
+- Linux with `systemd`, `nftables`, `iproute2`, cgroup v2.
+- Python 3 + PySide6 + `requests` (GUI).
+- Root privileges for routing/nftables changes (run API as a privileged service).