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/views/reports/ReportsIndex.vue

@@ -9,6 +9,11 @@
       <p>View printers with low or critical toner/supply levels</p>
       <span class="badge">Printers</span>
     </div>
+    <div class="report-card card" @click="router.push('/reports/warranty')">
+      <h3>Warranty Report</h3>
+      <p>Assets bucketed by coverage: expired, expiring soon, active</p>
+      <span class="badge">Warranty</span>
+    </div>
     <div v-for="report in reports" :key="report.id" class="report-card card" @click="runReport(report)">
       <h3>{{ report.name }}</h3>
       <p>{{ report.description }}</p>