feat(inventory): edit items in inventory grid

- Added 'Editar' button in inventory rows.

- Reused create modal as create/edit with pre-filled data.

- Added fields: unit, max_stock, tax_rate, description, is_active.

- Added /inventory/categories/all endpoint for flat category selector.

- Price/cost inputs are disabled for users without config.edit_prices.

pos/blueprints/inventory_bp.py

@@ -2271,6 +2271,22 @@ def list_inventory_subcategories(category_id):
         conn.close()
 
 
+@inventory_bp.route('/categories/all', methods=['GET'])
+@require_auth()
+def list_all_inventory_categories():
+    """Return all active categories (flat, with parent_id) for selectors."""
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        cur = conn.cursor()
+        cur.execute(
+            "SELECT id, name, parent_id FROM categories WHERE is_active = true ORDER BY name"
+        )
+        rows = cur.fetchall()
+        return jsonify({'categories': [{'id': r[0], 'name': r[1], 'parent_id': r[2]} for r in rows]})
+    finally:
+        conn.close()
+
+
 # ─── Global Tier Discounts ───────────────────────
 
 @inventory_bp.route('/tier-discounts', methods=['GET'])