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>

shopdb/core/models/asset.py

@@ -32,6 +32,7 @@ class AssetType(BaseModel):
     )
     description = db.Column(db.Text)
     icon = db.Column(db.String(50), comment='Icon name for UI')
+    color = db.Column(db.String(20), comment='CSS color for UI/map markers')
 
     def __repr__(self):
         return f"<AssetType {self.assettype}>"
@@ -215,8 +216,10 @@ class Asset(BaseModel, SoftDeleteMixin, AuditMixin):
         # Add related object names for convenience
         if self.assettype:
             result['assettypename'] = self.assettype.assettype
+            result['assettypecolor'] = getattr(self.assettype, 'color', None)
         if self.status:
             result['statusname'] = self.status.status
+            result['statuscolor'] = self.status.color
         if self.location:
             result['locationname'] = self.location.locationname
         if self.businessunit: