feat: initial vpndock stack

HAProxy SOCKS5 entry point + scalable purevpn-cli/microsocks exit nodes.
Supports up to 10 simultaneous connections (PureVPN limit), random location
selection from a predefined pool, and automatic reconnect to an unused
location on server-side drop.

vpn-node/servers.txt

@@ -0,0 +1,17 @@
+# PureVPN locations — one per line
+# Use country name ("United States") or 2-letter code ("US") — both work with:
+#   purevpn-cli --connect "United States"   OR   purevpn-cli -c "US"
+#
+# Run `purevpn-cli --list` to see all available locations after installing.
+# Lines starting with # are ignored.
+
+United States
+United Kingdom
+Germany
+Netherlands
+France
+Canada
+Australia
+Singapore
+Japan
+Switzerland