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>

.env.example

@@ -22,9 +22,11 @@ JWT_SECRET_KEY=change-this-to-another-secure-random-string
 
 # ---- Database (required) ----
 
-# Format: mysql+pymysql://<user>:<password>@<host>:<port>/<database>
+# Format: mysql+pymysql://<user>:<password>@<host>:<port>/<database>?charset=utf8mb4
 # In docker-compose, host is `db` (the service name).
-DATABASE_URL=mysql+pymysql://shopdb:CHANGE_ME@db:3306/shopdb_flask
+# The ?charset=utf8mb4 keeps the connection on utf8mb4; create the database as
+# utf8mb4 too (see docs/DEPLOY.md). Both must be utf8mb4 to match the schema.
+DATABASE_URL=mysql+pymysql://shopdb:CHANGE_ME@db:3306/shopdb_flask?charset=utf8mb4
 
 # ---- CORS (required, no wildcards in production) ----
 
@@ -67,3 +69,13 @@ ZABBIX_TOKEN=
 # EMPLOYEE_DB_USER=
 # EMPLOYEE_DB_PASSWORD=
 # EMPLOYEE_DB_NAME=wjf_employees
+
+# ---- cmmc_usb database (USB check-in/out) ----
+# Separate read-write MySQL DB used by the USB plugin to track device
+# check-in/out, lockers, and the check-in/out log. Leave unset if the feature
+# is not used; there is no safe default for the password, so an unset password
+# fails loud.
+# CMMC_USB_DB_HOST=
+# CMMC_USB_DB_USER=
+# CMMC_USB_DB_PASSWORD=
+# CMMC_USB_DB_NAME=cmmc_usb