Utilities: build the backbone once, add modules with the presses; four-module boiler hall and chiller compound

Phased build list for steam, cooling and hydraulics (launch, Duplex 1,
Duplex 2, Classic, options): everything cheap to oversize and costly to
retrofit (rooms, pads, headers and ring mains with a valved branch per
press position, tanks, HX frame, feeders, one sequencer) is built for the
five-press fleet at launch; boilers, chillers and hydraulic pump sets come
in identical modules as presses arrive. The Single 2.1 aggregate is
proposed as the first central pump set; per-branch isolation and filters.

Rooms sized for four modules each (user decision, estimates until vendor
footprints): boiler hall ~18 x 9 m for four 500 kg/h positions (fired case,
AIX DZL0.5 body), open screened chiller compound ~12.5 x 10.8 m with four
pads (250 kW at 40 C ~ Carrier 30RB 080-090), ~40 m2 pump and HX room; the
cooling tower pad of the water-cooled concept is dropped. Yard 178 -> ~379
m2. Four boilers carry ~8 presses with N+1; four 250 kW chillers carry the
five presses with CH-4 as reserve and no growth position unless the pads
take the ~350 kW frame (RFQ option).

- scale.md: yard table and basis, utility phasing section
- pressing-line.md: hydraulics phasing and re-quote questions
- steam-cooling.html: B-4 position, phasing and rooms card, details, RFQ
  questions (pw_sc_check clean)
- construction RFQ: yard table, sealed area 6,549 m2 (68 %)
- total-investment: added-scope row +73k to +122k USD (building rate on
  the ~200 m2 the yard grows by)
- Payap parts model: yard rebuilt from Params (blr_n, blr_inst, ch_*,
  bh_*, cy_*, pr_*), renders updated

docs/equipment/pressing-line.md

@@ -51,6 +51,20 @@ automated candidate). What it means:
   trench along the press rows. Open for the re-quote (below): whether the
   Single 2.1's own aggregate becomes part of the central plant or a
   standby, and whether the Classic can run from it.
+
+  Built to grow from one press (October 2026): the plant room is built at
+  full size, and the hydraulic and air ring mains are sized for the whole
+  fleet from the start, with a valved, capped tee at every press position,
+  the empty ones included, so a new press is connected without stopping
+  the others. The proposal for the Single 2.1's own aggregate, already
+  sized for the second press, is to set it in the plant room as the first
+  pump set on the ring main instead of beside the press; system 2 and the
+  Classic add pump sets in parallel on one manifold with the accumulators,
+  and a standby set follows. Each branch gets its own isolation valves and
+  filter: with one shared oil system, a contamination event otherwise
+  reaches every press. Steam and cooling follow the same pattern; the
+  phased list for all three is in
+  [scale](../scale.md#utility-phasing-backbone-once-modules-with-the-presses).
 - **Cell layout (October 2026).** Each Duplex system is one operator's
   cell, as sketched in [duplex-cell-layout-sketch.png](duplex-cell-layout-sketch.png)
   (arrangement only, not to scale):
@@ -84,7 +98,10 @@ automated candidate). What it means:
   of cooling with extruders and hydraulics, against the ~400 kg/h steam
   generator and ~250 kW cooling system that the 2024 quote's exclusions
   describe for one Duplex. The proposal is a bank of two 500 kg/h boilers
-  and three 250 kW chillers, one module per press stage; the layout, the
+  and three 250 kW chillers, one module per press stage, in a boiler hall
+  and a chiller compound built for four modules each
+  ([scale](../scale.md#detached-utility-yard-parking-and-what-that-moves));
+  the layout, the
   operating cases and the open RFQ questions are in
   [steam and cooling](../steam-cooling.html), the electrical consequences in
   [scale](../scale.md) and the costs in the
@@ -100,7 +117,10 @@ automated candidate). What it means:
   Classic's price, weight, power, steam and cooling figures; and the
   central hydraulic supply (an option the flyer offers) for the whole
   fleet, extendable to ten more Classics, including whether the Classic
-  can run from it.
+  can run from it, whether the presses hold their pressure from it over
+  the ring-main lengths of the hall, the filtration and isolation each
+  branch needs, and whether the Single 2.1's aggregate can be its first
+  pump set.
 
 The Pheenix AD12 leaves the plan; it stays in the
 [vendor landscape](../suppliers/vendor-landscape.md) as the comparison if