feat(configurator): pack right column alongside tall PO block — no dead space

Previous tightening removed the row-span but reintroduced a worse
problem: the tall PO block (with PO Pending + Expected By + chase
warning visible = ~250px) had only 2 small cells next to it
(Customer Job # / Job Sorting). 200px+ of vertical air below them
before row 3 started.

Layout now:
- Row 1: Customer (1-2) + Delivery Address (3-4)
- Rows 2-5 left: PO Block spans 4 grid rows (cols 1-2)
- Rows 2-5 right: 4 PAIRS of fields fill cols 3-4 in DOM order:
    Row 2: Customer Job # + Job Sorting
    Row 3: Material/Process + Lead Time
    Row 4: Payment Terms + Delivery Method
    Row 5: Pricelist + Quote Validity
- Row 6: Blanket SO + Invoice Strategy + conditional Deposit % / Progress %
  (full 4-col width, kicks in after the PO block ends)

CSS Grid auto-flow places the right-side cells in the open positions
next to the row-span-4 PO block. Each grid row auto-sizes to the max
of the cells in that row (PO block top portion or the right pair),
so PO block height naturally aligns with the 4 right rows — no dead
air on either side.

fusion_plating/fusion_plating_configurator/static/src/scss/express_order.scss

@@ -164,6 +164,7 @@
 
     .o_fp_xpr_cell.span-2 { grid-column: span 2; }
     .o_fp_xpr_cell.row-span-2 { grid-row: span 2; }
+    .o_fp_xpr_cell.row-span-4 { grid-row: span 4; }
     .o_fp_xpr_cell.required > label::after {
         content: " *";
         color: $xpr-bad;