feat(deps): vuetify 3→4 (batch 4 phase B, #1449)

Vuetify 4 is a Material-Design-3 styling refresh with revert snippets, not a
component-API overhaul. FC's exposure was small:

- Bump vuetify ^4, vite-plugin-vuetify ^2.1.0, vue ^3.5, engines node>=24.
- Restore the dropped global CSS reset (minimal reset from the upgrade guide) in
  Vuetify's own low-precedence reset layer, so FC's margin-zeroing assumptions hold.
- v-row prop→utility: 'dense' → density=compact (×3), align=center → class=align-center.
- v-snackbar: multi-line removed → min-height=68.
- v-autocomplete #item slot: item→internalItem (item now aliases raw) in TagPicker
  + GalleryFilterBar (item.raw.* → internalItem.raw.*).

ACCEPTED (cosmetic, operator reviews live per plan #158): MD3 typography
(text-body-2 ×73), non-uppercase buttons (v4 dropped the uppercase default),
MD3 elevation. CI verifies BUILD only — the LOOK is the live-review pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/package.json

@@ -4,7 +4,7 @@
   "private": true,
   "type": "module",
   "engines": {
-    "node": ">=22"
+    "node": ">=24"
   },
   "scripts": {
     "dev": "vite",
@@ -13,16 +13,16 @@
     "test:unit": "vitest run"
   },
   "dependencies": {
-    "vue": "^3.4.0",
+    "vue": "^3.5.0",
     "vue-router": "^5.0.0",
     "pinia": "^3.0.0",
-    "vuetify": "^3.5.0",
+    "vuetify": "^4.0.0",
     "@mdi/font": "^7.4.0"
   },
   "devDependencies": {
     "@vitejs/plugin-vue": "^6.0.0",
     "vite": "^8.0.0",
-    "vite-plugin-vuetify": "^2.0.0",
+    "vite-plugin-vuetify": "^2.1.0",
     "sass": "^1.71.0",
     "vitest": "^4.0.0",
     "@vue/test-utils": "^2.4.0",