feat(item): Agricultural Goods checkbox on Item

Add an item-level agricultural_goods flag so a document marked agricultural
can still contain non-agricultural items; tax reports filter on it.

Also fixes a duplicate "Item" key in the custom_fields dict (the second
entry shadowed the first), by merging both Item blocks into one so all
Item custom fields are created on a fresh install.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

jey_erp/custom_fields.py

@@ -1088,7 +1088,30 @@ def create_custom_fields():
                 insert_after='product_group_code',
                 in_list_view=1,
                 in_standard_filter=1
-            )
+            ),
+            # Marks an item as agricultural goods. A document can be flagged
+            # agricultural while only some of its items actually count as
+            # agricultural goods for tax reporting.
+            dict(
+                fieldname='agricultural_goods',
+                label='Agricultural Goods',
+                fieldtype='Check',
+                insert_after='product_category',
+                default=0,
+                in_standard_filter=1
+            ),
+            # Default expense account used by Landed Cost Voucher when this
+            # service item is added to the Landed Cost Taxes and Charges table.
+            # Hidden for stock items because LCV taxes are services only.
+            dict(
+                fieldname='default_landed_cost_account',
+                label='Default Landed Cost Account',
+                fieldtype='Link',
+                options='Account',
+                insert_after='is_stock_item',
+                depends_on='eval:doc.is_stock_item==0',
+                description='Used as the Expense Account when this service item is selected in a Landed Cost Voucher.',
+            ),
         ],
         "Item Group": [
             dict(
@@ -2104,20 +2127,6 @@ def create_custom_fields():
                 insert_after='custom_medical_insurance_column_break'
             ),
         ],
-        "Item": [
-            # Default expense account used by Landed Cost Voucher when this
-            # service item is added to the Landed Cost Taxes and Charges table.
-            # Hidden for stock items because LCV taxes are services only.
-            dict(
-                fieldname='default_landed_cost_account',
-                label='Default Landed Cost Account',
-                fieldtype='Link',
-                options='Account',
-                insert_after='is_stock_item',
-                depends_on='eval:doc.is_stock_item==0',
-                description='Used as the Expense Account when this service item is selected in a Landed Cost Voucher.',
-            ),
-        ],
         "Landed Cost Voucher": [
             # In-form button placed right above the Landed Cost (taxes) table,
             # mirroring the standard `get_items_from_purchase_receipts` button