feat(web): mobile dashboard UX polish (#28127)

* feat(web): mobile dashboard UX polish

Bottom sheets for sidebar theme/language pickers on narrow viewports with
enter/exit animation and drag-to-close; inline header badges beside titles;
bottom padding on the route outlet for scroll clearance; profiles loading uses a
unicode braille spinner; align profile/cron card actions to the top; viewport-fit
cover and supporting layout tweaks across dashboard pages.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Fix Nix web npm hash and mobile sheet accessibility.

Align fetchNpmDeps in nix/web.nix with web/package-lock.json for CI. Improve BottomPickSheet backdrop labeling, avoid aria-hidden on the dialog during exit animation, and wire theme/language sheets with listbox semantics and localized dismiss labels.

Co-authored-by: Cursor <cursoragent@cursor.com>

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Co-authored-by: Cursor <cursoragent@cursor.com>

web/package.json

@@ -24,6 +24,7 @@
     "@xterm/xterm": "^6.0.0",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
+    "flag-icons": "^7.5.0",
     "gsap": "^3.15.0",
     "leva": "^0.10.1",
     "lucide-react": "^0.577.0",