Fix bin/publish: copy docs.dist from project root

Fix bin/publish: use correct .env path for rspade_system
Fix bin/publish script: prevent grep exit code 1 from terminating script

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

node_modules/laravel-mix/src/Engine.js

@@ -0,0 +1,10 @@
+const semver = require('semver');
+const pkg = require('../package.json');
+
+module.exports.assertSupportedNodeVersion = function assertSupportedNodeVersion() {
+    if (!semver.satisfies(process.versions.node, pkg.engines.node)) {
+        throw new Error(
+            `You are using an unsupported version of Node. Please update to at least Node v12.14`
+        );
+    }
+};