Add custom fields + warranty plugin, rework settings into two-pane shell

Feature work from the 2026-07 session:

Settings IA
- Replace the flat 27-card settings hub with a persistent two-pane shell
  (SettingsLayout.vue): grouped, searchable left rail + content pane.
- Nest all settings/* routes under the shell via router post-processing;
  shared nav catalog in settingsNav.js. Group by asset class (PCs, Printers,
  Equipment, Network) so per-type settings stop scattering.

Custom fields (core)
- customfields + customfieldvalues tables (migration 7d14), CRUD API at
  /api/customfields, per-asset value get/save.
- Settings management page + reusable CustomFieldsSection (detail) and
  CustomFieldsInputs (form) wired into all four asset types.

Warranty (new plugin)
- plugins/warranty: warranties + warrantyassets (migration 7d15), derived
  coverage status, provider abstraction (manual now; Dell/Lenovo/HP stubs).
- API CRUD + per-asset panel + report buckets; WarrantyPanel on all four
  detail pages; Warranties management page; Warranty report + Reports card.
- Seed warranty.* permissions.

Printer drivers
- printerdrivers table (migration 7d13) linked to printer models; drivers now
  surface on the matching printer's detail page.

Other
- PCDetail rebalanced (Network + Status + Warranty + custom fields on the right).
- Rename PCs list "Features" column to "Remote Access"; fix badge hover underline.
- Drop equipment islocationonly field.
- Centralize asset-type label/route maps into utils/assetTypes.js.

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

frontend/src/router/index.js

@@ -1,10 +1,39 @@
 import { createRouter, createWebHistory } from 'vue-router'
 import { useAuthStore } from '../stores/auth'
 import AppLayout from '../views/AppLayout.vue'
+import SettingsLayout from '../views/settings/SettingsLayout.vue'
 
 // Auto-discover all route modules from routes/ directory
 const routeModules = import.meta.glob('./routes/*.js', { eager: true })
-const appChildren = Object.values(routeModules).flatMap(m => m.default)
+const rawChildren = Object.values(routeModules).flatMap(m => m.default)
+
+// Gather the settings pages (spread across plugin route files) and nest them
+// under a single two-pane shell so the grouped rail stays put while the right
+// pane swaps. Slides is a sidebar page that happens to live at /settings/slides;
+// keep it full-width (not inside the settings rail).
+const SETTINGS_STANDALONE = new Set(['settings/slides'])
+const settingsChildren = []
+const otherChildren = []
+for (const route of rawChildren) {
+  const path = route.path
+  if (path === 'settings') {
+    // Old index becomes the shell's default child (keeps name 'settings').
+    settingsChildren.unshift({ ...route, path: '' })
+  } else if (typeof path === 'string' && path.startsWith('settings/') && !SETTINGS_STANDALONE.has(path)) {
+    settingsChildren.push({ ...route, path: path.replace(/^settings\//, '') })
+  } else {
+    otherChildren.push(route)
+  }
+}
+const appChildren = [
+  ...otherChildren,
+  {
+    path: 'settings',
+    component: SettingsLayout,
+    meta: { requiresAuth: true, requiresAdmin: true },
+    children: settingsChildren,
+  },
+]
 
 const routes = [
   {