perf(frontend): drop pdf chunk from eager preload, bump deps

Rollup co-located Vite's __vitePreload helper inside the lazy pdf
chunk, so the entry modulepreloaded all 588KB (172KB gzip) on every
visit just to reach the helper. Pin preload + CJS interop helpers to
the always-eager vue chunk instead — pdf now loads only on PDF
download. ~172KB gzip off initial load.

Also remove the dead supabase manualChunks branch (SDK is tree-shaken
at build with no env vars, leaving an empty chunk + warning).

Bump vue 3.5.25->3.5.38, dompurify 3.4.0->3.4.9, supabase 2.106->2.108,
@vue/test-utils, @vitejs/plugin-vue, @lhci/cli. Prod audit clean.

Author: Harsh Patadia