Initial release: procd service and LuCI app for copyparty

OpenWrt procd service script and LuCI JavaScript interface for
copyparty (https://github.com/9001/copyparty), a self-hosted file
sharing server.

Features:
- procd service with UCI-driven volumes, accounts, and TLS cert
- LuCI view: settings, volume/account grids, live status + start/stop
- ACME TLS support via combined key+fullchain PEM (--cert flag)
- Auto-respawn and reload-on-config-change via service_triggers

usr/share/luci/menu.d/luci-app-copyparty.json

@@ -0,0 +1,14 @@
+{
+	"admin/services/copyparty": {
+		"title": "Copyparty",
+		"order": 70,
+		"action": {
+			"type": "view",
+			"path": "copyparty"
+		},
+		"depends": {
+			"acl": [ "luci-app-copyparty" ],
+			"uci": { "copyparty": true }
+		}
+	}
+}

usr/share/rpcd/acl.d/luci-app-copyparty.json

@@ -0,0 +1,11 @@
+{
+	"luci-app-copyparty": {
+		"description": "Grant UCI access for luci-app-copyparty",
+		"read": {
+			"uci": [ "copyparty" ]
+		},
+		"write": {
+			"uci": [ "copyparty" ]
+		}
+	}
+}