Payap scenario: parametric BIM model of the whole plant on a square plot

A separate FreeCAD 26.3 model (the Mueang Chi model is untouched) sites
the plant on a 110 m square placeholder plot of Payap land, built from
BIM objects (Arch Site, Buildings and Levels, walls, slabs, columns,
beams, a ramp, Spaces with computed areas, Equipment). Every object sits
on an expression-driven base, so the Params sheet drives plot, setbacks,
floor level, building sizes, fire wall line and office gap (checked:
plot 110 to 120 m and factory 84 to 90 m, everything followed).

- Factory 84 x 25 m, production only, in process order along a 54 m
  glazed corridor; press hall 465 m2 with the October fleet (two Duplex
  systems, each EX 50 + EX 35, and the Classic); crane to the fire wall;
  machine door and 12 m ramp at the north-west corner.
- Office building 24 x 15 m, 12 m away on its own slab with a covered
  link: reception, offices, meeting/training, mastering and cutting,
  listening, IT, archive. Resolves the crane-zone conflict of the old
  sketch.
- Utility yard behind the press hall (boiler and chiller flagged for
  re-sizing), gate, truck apron, car park, service road.
- site-candidates: new section and plot-fit note; crane doc: conflict
  resolved, 54 m corridor; README bullet and layout lines; the old
  sketch is labelled as Mueang Chi with the earlier fleet.

README.md

@@ -123,9 +123,17 @@ The detail lives in dedicated documents:
   it costs
 - [Production hall layout sketch](docs/production-hall-layout-sketch.png):
   a rough BIM sketch in FreeCAD (`docs/production-hall-layout-sketch.FCStd`)
-  of the 60 x 25 m phase 1 hall: zones in process order along the visitor
-  corridor, the crane zone, room-in-room boxes and the main equipment; every
-  position is an estimate
+  of the 60 x 25 m phase 1 hall at Mueang Chi, with the fleet before
+  October 2026: zones in process order along the visitor corridor, the
+  crane zone, room-in-room boxes and the main equipment; every position is
+  an estimate
+- [Payap scenario model](docs/cnx_vinyl_parametric_payap.png): a parametric
+  BIM model in FreeCAD 26.3 (`docs/cnx_vinyl_parametric_payap.FCStd`,
+  [isometric](docs/cnx_vinyl_parametric_payap-iso.png)) of the whole plant
+  on a square placeholder plot of Payap land: an 84 x 25 m production-only
+  factory with the five-press fleet, a separate office building for
+  offices, mastering and IT, the utility yard and site access, all driven
+  by one parameter sheet
 - [Process logging and traceability](docs/traceability.md): end-to-end
   per-order traceability for customers, batch genealogy from audio file to
   shipment, and the requirements this sets for the factory software
@@ -224,13 +232,16 @@ docs/
 ├── artist-platform.md     Upload, price calculator, fan-funded pressing
 ├── biomass.md             Biomass fuel strategy and the 60 rai coppice idea
 ├── boi.md                 BOI promotion strategy and requirements
+├── cnx_vinyl_parametric_payap.FCStd   Payap scenario parametric BIM model
+├── cnx_vinyl_parametric_payap.png     Top view of the Payap model
+├── cnx_vinyl_parametric_payap-iso.png Isometric view of the Payap model
 ├── crane-workshop-tours.md Overhead crane, workshop, visitor corridor
 ├── digital-factory.md     Data platform, NixOS/Clan fleet, acquisition, app
 ├── facility-security.md   Security, HVAC, fire and life safety, compliance
 ├── payap-partnership.md   Joint student programmes with Payap University
 ├── plant-operation.html   Animated plant overview (simulated SCADA)
 ├── process-flow.md        Audio file to delivered record, with all checks
-├── production-hall-layout-sketch.FCStd  Rough BIM layout sketch of the hall
+├── production-hall-layout-sketch.FCStd  Rough BIM sketch, Mueang Chi hall (earlier fleet)
 ├── production-hall-layout-sketch.png    Top view of the sketch
 ├── production-timeline.md Order turnaround, stage by stage
 ├── project-timeline.md    Calendar to first paying release, critical path