docs: refresh integration versions and wire new docs into sidenav

integrations.mdx:
- Adds a callout at the top about version-pinning (the CDN URLs use
  specific versions for reproducibility, but third-party libraries
  publish independently of AdminLTE; check upstream before copying
  into production)
- Bumps drifted versions: tom-select 2.3.1->2.6.1, filepond 4.32.7->
  4.32.12, easymde 2.18.0->2.21.0, apexcharts 4.4.0->5.12.0 (major),
  chart.js 4.4.4->4.5.1, glightbox 3.3.0->3.3.1
- Other versions (flatpickr, nouislider, pickr, imask, dropzone,
  quill, toast-ui, tabulator, fullcalendar, sortablejs) were
  already current

_sidenav.astro:
- Adds Layout Blueprint after Layout (logical pairing -- "the lower-
  level CSS classes" then "the high-level region structure")
- Adds Recipes after Layout Blueprint
- Adds Deployment after Recommended Integrations (closing chapter of
  the "shipping a real app" arc)
- Adds Plugins Overview as the first item in the JavaScript submenu
  so readers see the index before diving into individual plugins