refactor: migrate custom fields from fixtures to exported customizations

[engahmed1190]

Summary

• Migrated custom fields from fixture-based (custom_field.json) to exported customizations (pos_next/custom/*.json)
• Removed Print Format fixture in favor of exported print format
• Removed Custom Field and Print Format entries from hooks.py fixtures

Known Issues — Corrupted / Foreign Fields

This branch contains fields exported from the site database that do NOT belong to POS Next. The export-customizations command dumped ALL custom fields on the site, not just POS Next ones. The following must be cleaned up before merge:

Foreign Custom Fields (from other apps — KSA/UAE localization)

File	Field	Source	Indicator
item.json	Item-is_zero_rated	KSA/UAE VAT localization	is_system_generated: 1, module: null
item.json	Item-is_exempt	KSA/UAE VAT localization	is_system_generated: 1, module: null
sales_invoice.json	Sales Invoice-company_trn	KSA/UAE localization	is_system_generated: 1, module: null, fetches company.tax_id
sales_invoice.json	Sales Invoice-customer_name_in_arabic	KSA/UAE localization	is_system_generated: 1, module: null
sales_invoice.json	Sales Invoice-ksa_einv_qr	KSA e-invoicing	is_system_generated: 1, module: null
sales_invoice_item.json	Sales Invoice Item-is_zero_rated	KSA/UAE VAT localization	is_system_generated: 1, module: null
sales_invoice_item.json	Sales Invoice Item-is_exempt	KSA/UAE VAT localization	is_system_generated: 1, module: null
pos_profile.json	POS Profile-custom_brands_table	Another feature branch (KCSC)	module: null, references POS Brands Detail child table

Site-Specific Property Setters (should NOT be exported)

• item.json: 7 property_setters (naming_series hidden/options/reqd, item_code hidden/reqd, barcodes hidden, field_order)
• sales_invoice.json: 14 property_setters (naming_series options, various hidden/print_hide tweaks)
• sales_invoice_item.json: 4 property_setters (barcode hidden, discount_account, target_warehouse)
• pos_profile.json: 1 property_setter (field_order)

Site-Specific Custom Perms (already handled by custom_docperm.json fixture)

• item.json: 9 custom_perms (all ERPNext standard roles + POSNext Cashier — duplicated)
• sales_invoice.json: 3 custom_perms (duplicated from custom_docperm.json)
• pos_profile.json: 3 custom_perms (duplicated from custom_docperm.json)

Phantom Field Reference (pre-existing bug)

• pos_profile.json line 163: "insert_after": "posa_default_sales_order" — this field does NOT exist anywhere in the codebase

Unnecessary Files (zero POS Next customizations)

• item_barcode.json — only contains a site-specific property_setter
• packed_item.json — only contains a site-specific property_setter

What SHOULD remain (POS Next only, module: "POS Next")

DocType	Field	Status
Item	custom_company	OK
Sales Invoice	posa_pos_opening_shift	OK
Sales Invoice	posa_is_printed	OK
POS Profile	posa_cash_mode_of_payment	OK
POS Profile	posa_allow_delete	OK
POS Profile	posa_block_sale_beyond_available_qty	OK (fix insert_after)
Mode of Payment	is_wallet_payment	OK

Action Required

Each custom JSON file needs to be cleaned to contain only fields with module: "POS Next", remove all foreign property_setters, remove duplicated custom_perms, and delete item_barcode.json and packed_item.json entirely.