chore: rebuild dist for v4.0.0 stable

Regenerates dist/ and src/html/public/ for all the changes queued in
this batch:

- 18 new demo pages (apps, page templates, mailbox, data tables, forms
  split, wizard, integrations docs)
- color-mode toggle wiring shipped on every page via _scripts.astro
- Bug fixes for issues #6010, #6019, #6020, #6021, #6026, #6028
- Updated SCSS for table-head-fixed dark-mode support and the new
  fixed-header sidebar sticky rule
- Updated fullscreen plugin (toggles .d-none) and refreshed
  adminlte.js / adminlte.min.js

Bundle sizes still well within the bundlewatch budget:
- CSS  43.76 KB gz  (budget 46 KB)
- JS    5.2  KB gz  (budget  5.2 KB)