PERF.75 Code: deep clones by JSON round trip (205 sites, some inside merge loops) and 24 timers polling faster than once a second

Perf-relevant sloppiness confirmed by reading the top sites. Clones: 205 JSON.parse(JSON.stringify()) plus 112 clone helpers; takeoffcraft/a Discord member/learn.js clones inside merge loops (11 sites), clipboard.js and dwg-keep.js clone document-sized objects: structuredClone or a cloneDoc that copies only what changes. Timers: cadcraft live.js:763 and markupcraft live-ui.js:71 setInterval(push, 33) build presence and JSON.stringify it 30 times a second while idle; hazard-ui and people-ui animate with setInterval 33; countall-ui waits on a worker with a 20 ms poll; plc-ui 50 ms; 250 to 500 ms pollers elsewhere. Change: event-driven pushes with a dirty flag, requestAnimationFrame for animation, promise-based worker replies; a check that lists any setInterval under 1 s. Also: a console.log in bimcraft fem/frame-push.js:155 inside the solver loop, 12 new RegExp inside loops (takeoffcraft xlsx-read.js:74 on file open).