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>

plugins/slides/models/__init__.py

@@ -0,0 +1,5 @@
+"""Slides plugin models."""
+
+from .tvslide import TvSlide
+
+__all__ = ['TvSlide']

plugins/slides/models/tvslide.py

@@ -0,0 +1,35 @@
+"""Slide model for the TV dashboard / screensaver slideshows."""
+
+from shopdb.api import db
+
+
+class TvSlide(db.Model):
+    """One slide image in a surface's playlist.
+
+    Image files live on disk at instance/slides/<surface>/<filename>; this row
+    holds the play order + per-slide duration. Files are the source of truth for
+    existence - rows whose file is gone are ignored and pruned.
+    """
+    __tablename__ = 'tvslides'
+
+    slideid = db.Column(db.Integer, primary_key=True)
+    surface = db.Column(db.String(20), nullable=False, index=True)
+    filename = db.Column(db.String(255), nullable=False)
+    sortorder = db.Column(db.Integer, default=0, nullable=False)
+    seconds = db.Column(db.Integer, default=0, nullable=False)  # 0 = use default interval
+    uploadeddate = db.Column(db.DateTime, default=db.func.now())
+
+    # No DB-level unique on (surface, filename): utf8mb4 pushes that index past
+    # MySQL 5.6's 767-byte limit. Upload unique-renames, so dupes can't occur.
+    __table_args__ = (
+        db.Index('idx_tvslide_surface', 'surface'),
+    )
+
+    def to_dict(self):
+        return {
+            'slideid': self.slideid,
+            'surface': self.surface,
+            'filename': self.filename,
+            'sortorder': self.sortorder,
+            'seconds': self.seconds,
+        }