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.

.env.example

@@ -0,0 +1,16 @@
+# Copy to .env and fill in your details:
+#   cp .env.example .env
+
+# ── PureVPN credentials ───────────────────────────────────────────────────────
+PUREVPN_USER=your@email.com
+PUREVPN_PASS=yourpassword
+
+# ── Location pool (comma-separated, no spaces around commas) ─────────────────
+# Each vpn-node picks randomly from this list and rotates on reconnect.
+# Supports full country names or 2-letter codes — both work with purevpn-cli.
+# Leave blank to use vpn-node/servers.txt instead.
+#
+PUREVPN_LOCATIONS=United States,United Kingdom,Germany,Netherlands,France,Canada,Australia,Singapore,Japan,Switzerland
+
+# ── SOCKS5 listen port on the host (browser points here) ─────────────────────
+SOCKS5_PORT=1080