Data centres: multi-storey shell, racks and pods, cooling, fire safety, power

datacentre.rhai (palette groups Data centre, Cooling, Fire safety, Power):

- dc_building: multi-storey shell (storeys of storey_h), walls in pieces,
  slabs, roof with parapet, louvres, front door and loading dock; levels
  cut it open storey by storey
- raised_floor; rack_row and dc_pod (cabinets by U, width, depth,
  equipment, fill, doors, LEDs; in-row coolers; cold / hot aisle
  containment with vent tiles, roof, end doors, ceiling duct, airflow);
  dc_cage for colocation
- crah, chiller (air-cooled, dry, adiabatic), cooling_tower, pipe_run
- smoke_detectors (grid + coverage), fire_pipe (VESDA, sprinkler, gas),
  gas_bank (Novec 1230, FM-200, Inergen sized for its halls), fire_device
  (panels, call points, abort switches, beacons, extinguishers)
- power_cab (UPS, battery, PDU, switchgear, RPP), busway, cable_tray,
  transformer
- tooltips sum IT load, kW/m2, cooling redundancy per storey, UPS load,
  battery runtime, plant cooling and agent quantity (warning when short)

Engine and stdlib:

- part_hidden(o) in house.rhai: parts on closed storeys inside a
  dc_building are not drawn (they only made sort cycles under the slab
  above); house parts, furniture and people use it. Existing examples
  render byte-identical.
- overhead services sort in their own "ceiling" layer with tight boxes
- sort records which sprites each broken cycle involved; isokit check
  names them (Rendered.cycle_at)

examples/datacentre (three storeys and a roof plant), Data centre demo in
the web Studio, tests, SCRIPTING/README/ROADMAP, MCP instructions.

web/web.js

@@ -367,7 +367,7 @@ function injectUI() {
     '<h3>Projects</h3>' +
     '<div class="wb-cur" id="wb-cur"></div>' +
     '<ul class="wb-plist" id="wb-plist"></ul>' +
-    '<div class="wb-new"><input id="wb-ntitle" placeholder="Title of a new project" autocomplete="off"><button type="button" id="wb-ncreate">New project</button><button type="button" id="wb-ndemo" title="A fresh copy of the demo scene">Demo copy</button><button type="button" id="wb-nhouse" title="A house built from parts: walls, windows, doors, floors, furniture">House demo</button><button type="button" id="wb-nfactory" title="Presses making goods at a set rate, conveyors carrying them">Factory demo</button><button type="button" id="wb-nstreets" title="Streets with sidewalks, a rounded corner, junctions and a roundabout">Streets demo</button><button type="button" id="wb-ncountry" title="Elephants, deer, boar, beehives and a wildflower meadow; a lane, fence and hedgerow at an angle">Country demo</button></div>' +
+    '<div class="wb-new"><input id="wb-ntitle" placeholder="Title of a new project" autocomplete="off"><button type="button" id="wb-ncreate">New project</button><button type="button" id="wb-ndemo" title="A fresh copy of the demo scene">Demo copy</button><button type="button" id="wb-nhouse" title="A house built from parts: walls, windows, doors, floors, furniture">House demo</button><button type="button" id="wb-nfactory" title="Presses making goods at a set rate, conveyors carrying them">Factory demo</button><button type="button" id="wb-nstreets" title="Streets with sidewalks, a rounded corner, junctions and a roundabout">Streets demo</button><button type="button" id="wb-ncountry" title="Elephants, deer, boar, beehives and a wildflower meadow; a lane, fence and hedgerow at an angle">Country demo</button><button type="button" id="wb-ndc" title="A three-storey data centre: power room, a hall with cold aisle containment, GPU pods with hot aisle containment, cages, cooling, fire detection and suppression">Data centre demo</button></div>' +
     '<div class="wb-drop" id="wb-drop">Import: drop a project folder or .zip here, or <button type="button" id="wb-izip" title="Import a project .zip into this browser">.zip…</button><button type="button" id="wb-idir" title="Copy a project folder into this browser">folder…</button>' +
     (canOpenFolder ? '<span class="st-grow"></span><button type="button" id="wb-ofolder" title="Edit the files in the folder on disk directly; changes made there show up live">Open folder live…</button>' : "") + "</div>" +
     '<p class="st-help">Projects are kept in this browser. ' + (canOpenFolder ? "A folder opened live is edited on disk, so agents (<b>isokit mcp</b>), editors and git see the same files." : "To edit a folder on disk directly, use Chrome or Edge.") + "</p>" +
@@ -421,6 +421,7 @@ function wireProjects() {
   $("wb-nfactory").addEventListener("click", async function () { openProject((await createProject(await demoFiles("factory.json"))).id); });
   $("wb-nstreets").addEventListener("click", async function () { openProject((await createProject(await demoFiles("streets.json"))).id); });
   $("wb-ncountry").addEventListener("click", async function () { openProject((await createProject(await demoFiles("country.json"))).id); });
+  $("wb-ndc").addEventListener("click", async function () { openProject((await createProject(await demoFiles("datacentre.json"))).id); });
   $("wb-izip").addEventListener("click", function () { $("wb-fzip").click(); });
   $("wb-idir").addEventListener("click", function () { $("wb-fdir").click(); });
   $("wb-fzip").addEventListener("change", function () { var f = this.files[0]; if (f) importZip(f); this.value = ""; });