Redesign admin UI: unified tabbed console, humanized and paginated stats

- Unify /admin/login and /admin/stats into a single /admin page with tabs
  (Token stats default, credential login); old paths redirect to /admin.
- Restyle from dark glass-morphism to a clean light theme (single accent,
  system font stack, 1px-bordered cards, generous whitespace).
- Humanize token counts with K/M/B suffixes via a humanNum template func.
- Paginate recent requests client-side (10 per page) with a compact pager.
- Drop the database path from the UI.
- Fix mobile horizontal overflow caused by grid min-width:auto.

.gitignore

@@ -13,3 +13,4 @@ extension/
 tmp/
 temp/
 source/
+output/