feat: category icons sync + unknown type dashboard widget

- Synced categories table: added Equipment/Appliances with icons,
  removed unused Furniture/Utensils & Serveware
- Updated seed data to match real asset categories
- Added category_health query to /api/stats (finds asset categories
  not in the categories lookup table)
- Added Category Health card to dashboard UI (red warning, shown
  only when unmapped categories exist)

admin_server.py

@@ -310,8 +310,9 @@ def _seed_if_empty(conn: sqlite3.Connection, table: str, columns: tuple, rows: l
 def _seed_data(conn: sqlite3.Connection):
     """Insert default seed data for lookup tables."""
     _seed_if_empty(conn, "categories", ("name", "icon"), [
-        ("Furniture", "🪑"), ("Appliances", "🔌"),
-        ("Utensils & Serveware", "🍽️"), ("Equipment", "⚙️"), ("Other", "📦"),
+        ("Bev", "🥤"), ("Snack", "🍿"),
+        ("Food", "🍔"), ("Equipment", "🔧"),
+        ("Appliances", "🔌"), ("Other", "📦"),
     ])
     _seed_if_empty(conn, "key_names", ("name",), [
         ("MK500",), ("Green Dot",), ("Red Key",), ("Blue Key",),
@@ -1526,6 +1527,19 @@ def get_stats():
     ).fetchall()
     by_make = {r["make"]: r["cnt"] for r in makes}
 
+    # Find asset categories not in the categories lookup table
+    unmapped = conn.execute(
+        """SELECT a.category AS name, COUNT(*) AS cnt
+           FROM assets a LEFT JOIN categories c ON a.category = c.name
+           WHERE c.id IS NULL AND a.category IS NOT NULL AND a.category != ''
+           GROUP BY a.category ORDER BY cnt DESC"""
+    ).fetchall()
+    category_health = {
+        "unmapped": [{"name": r["name"], "count": r["cnt"]} for r in unmapped],
+        "total_categories": len(by_category),
+        "unmapped_count": len(unmapped),
+    }
+
     conn.close()
     return {
         "total_assets": total_assets,
@@ -1538,6 +1552,7 @@ def get_stats():
         "top_visited": top_visited_list,
         "time_on_site": time_on_site,
         "by_make": by_make,
+        "category_health": category_health,
     }