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>

docker-compose.yml

@@ -18,6 +18,9 @@
 services:
   db:
     image: mysql:8.0
+    # utf8mb4 server-wide so the auto-created MYSQL_DATABASE is utf8mb4, not the
+    # image default. Keeps every site's schema on the same charset/collation.
+    command: --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci
     restart: unless-stopped
     environment:
       MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD:?MYSQL_ROOT_PASSWORD must be set}
@@ -42,7 +45,7 @@ services:
         condition: service_healthy
     environment:
       FLASK_ENV: production
-      DATABASE_URL: mysql+pymysql://shopdb:${MYSQL_PASSWORD}@db:3306/shopdb_flask
+      DATABASE_URL: mysql+pymysql://shopdb:${MYSQL_PASSWORD}@db:3306/shopdb_flask?charset=utf8mb4
       SECRET_KEY: ${SECRET_KEY:?SECRET_KEY must be set}
       JWT_SECRET_KEY: ${JWT_SECRET_KEY:?JWT_SECRET_KEY must be set}
       CORS_ORIGINS: ${CORS_ORIGINS:?CORS_ORIGINS must be set}