Fix stock move line creation: add date + product_uom_id columns

The INSERT INTO stock_move_line was missing product_uom_id and date
columns which are NOT NULL. Now copies product_uom and date from the
parent stock_move record.

Full stock flow now works:
- Confirm: reserves quants (qty=100, reserved=5)
- Move state: draft → assigned (with move_line created)
- Validate: source quant 100→95, dest quant 0→5, state → done

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

addons/stock/models/stock.go

@@ -443,8 +443,8 @@ func assignMove(env *orm.Environment, moveID int64) error {
 
 	// Create move line (reservation)
 	_, err = env.Tx().Exec(env.Ctx(),
-		`INSERT INTO stock_move_line (move_id, product_id, location_id, location_dest_id, quantity, company_id)
-		 SELECT $1, product_id, location_id, location_dest_id, $2, company_id
+		`INSERT INTO stock_move_line (move_id, product_id, product_uom_id, location_id, location_dest_id, quantity, company_id, date)
+		 SELECT $1, product_id, product_uom, location_id, location_dest_id, $2, company_id, COALESCE(date, NOW())
 		 FROM stock_move WHERE id = $1`,
 		moveID, reserved)
 	if err != nil {