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.

crates/isokit-script/stdlib/people.rhai

@@ -3,30 +3,37 @@
 fn people_colours() { ["hivis", "guest1", "guest2", "guest3", "guest4", "guide", "suit"] }
 
 fn meta_person() {
-    #{ label: "Person", category: "People", icon: "🧍",
+    #{ label: "Person", category: "People", icon: "🧍", storey: true,
        props: [
          #{ key: "cls", type: "choice", def: "hivis", choices: people_colours(), label: "Clothes" },
          #{ key: "seated", type: "bool", def: false, label: "Seated" },
        ] }
 }
+// People are left out like house parts (on a storey above the one a level
+// cuts open, or inside a closed data centre storey); on a raised floor they
+// stand on its top.
 fn prefab_person(o) {
+    if part_hidden(o) { return; }
+    let z = dc_lift(o);
     let s = sprite();
-    if o.p.seated { s.sit(0.0, 0.0, 0.0, o.p.cls); } else { s.person(0.0, 0.0, 0.0, o.p.cls); }
+    if o.p.seated { s.sit(0.0, 0.0, z, o.p.cls); } else { s.person(0.0, 0.0, z, o.p.cls); }
 }
 
 fn meta_crowd() {
-    #{ label: "Crowd", category: "People", icon: "👥",
+    #{ label: "Crowd", category: "People", icon: "👥", storey: true,
        props: [
          #{ key: "n", type: "int", def: 5, min: 2, max: 40, step: 1, label: "People" },
          #{ key: "r", type: "float", def: 2.0, min: 0.6, max: 15.0, step: 0.1, label: "Spread (m)" },
        ] }
 }
 fn prefab_crowd(o) {
+    if part_hidden(o) { return; }
+    let z = dc_lift(o);
     let cols = ["guest1", "guest2", "guest3", "guest4", "hivis"];
     for i in 0..o.p.n {
         // one sprite each, scattered deterministically in a disc
         let a = hash(i * 1.7 + o.x) * 6.2832;
         let r = o.p.r * hash(i * 3.3 + o.y).sqrt();
-        sprite().person(r * a.cos(), r * a.sin(), 0.0, cols[i % 5]);
+        sprite().person(r * a.cos(), r * a.sin(), z, cols[i % 5]);
     }
 }