Adopt @simpleworkjs/frontend's messages/modal/validate modules

Same swap as sso-manager-node/jump-host: vendored app.util.actionMessage/
actionConfirm replaced by @simpleworkjs/frontend's app.messages.action/
confirm (real HTML-escaping, toast fallback); vendored val.js replaced by
the package's app.validate.js.

proxy's host/target/hostname validation rules (mirrored from the backend's
utils/hostname_validate.js — wildcard DNS patterns, not something other
apps need) move to public/js/app.js, registered via $.validateSettings,
since they're proxy-specific and don't belong in the shared package's
generic rule set (eq/user/password/ip).

app.api/app.auth/app.pubsub/app.socket in app-base.js are untouched, same
reasoning as sso-manager-node's PR.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

nodejs/package.json

@@ -21,8 +21,9 @@
   "dependencies": {
     "@fortawesome/fontawesome-free": "^7.3.0",
     "@popperjs/core": "^2.11.8",
-    "@simpleworkjs/conf": "^1.2.0",
     "@simpleworkjs/app-stack": "^1.0.0",
+    "@simpleworkjs/conf": "^1.2.0",
+    "@simpleworkjs/frontend": "^0.2.5",
     "@simpleworkjs/ldap": "^1.0.0",
     "@simpleworkjs/oidc-client": "^1.0.0",
     "acme-client": "^5.4.0",