Add Varaverk plugin scaffold (PHP, unRAID native)

Plugin lives in Plugin/ — invisible to User Script Plugin.
dev_install.sh symlinks into /usr/local/emhttp/plugins/varaverk/ for development.

Pages: Monitor (5s poll), Scheduler (orchs + Advanced children, toggle + cron),
Config (raw editor, host-aware file access), Docs (markdown + live $VAR substitution).

API endpoints: monitor.php (JSON), scheduler.php (writes schedule.json + cron.d),
config.php (writes conf files with host permission check).

Includes: config.php (parser, host detection, var map), scheduler.php (job tree,
cron.d rebuild), monitor.php (docker, GPU, resources, fallback, transcode),
docs.php (file tree, var substitution, Parsedown renderer).

Plugin/usr/local/emhttp/plugins/varaverk/js/varaverk.js

@@ -0,0 +1,9 @@
+// Varaverk — shared JS utilities
+// Page-specific JS lives inline in each page partial.
+
+// Flash a status element briefly then fade
+function vvFlashStatus(el, msg, ok) {
+  el.textContent = msg;
+  el.style.color = ok ? '#4caf50' : '#f44336';
+  setTimeout(() => { el.textContent = ''; }, 3000);
+}