feat(demo): add the CEO-stature demo and antiquity bench precision

[the-simian]

What changed

Antiquity forge bench

• Add inch and centimeter to the antiquity bench's from/to options (ordered by metric size).
• The bench slider now resolves to the 100ths place for the modern units (inch, centimeter, foot, meter); ancient units keep their integer steps. Mechanically, the shared Bench swaps round1 for a new roundToStep(value, step) in lib/math.ts, so it rounds to each unit's own granularity. Other kits keep integer steps, so their behavior is unchanged.
• kits/antiquity now re-exports centimeter alongside foot/inch/meter/statuteMile.

New section: "how tall is your CEO?"

A flagship section appended last in the antiquity kit:

• Stair-step ruler (full width): the X axis is the height axis. Faint stand-ins sit at the 5/6/7 ft marks; the two selected people drop in at the X position matching their height and are stretched vertically to it (height-only), so a taller person reads as further right and taller. Subject is --uf-accent, reference is --uf-accent-2.
• Two pickers (subject / reference), one component used twice: a grouped roster select (Executives / Leaders) plus a custom-height mode whose inches slider projects to ft′in″ (primary) with cm beside it (muted), live, via forge.
• Center reading: subject as a percentage of the reference, plus the signed inch delta.
• Ancient readout: any of the 17 bench length units; forges both heights and their delta into the chosen unit.
• 34-figure roster (tech execs and historical leaders) with a "popularly reported, approximate" disclaimer; heights are encoded as reported figures, not verified measurements.

Two custom human glyphs

figure-glyph (plain, for stand-ins) and exec-glyph (tie, for the two selected), both with fill lifted to a color prop (default currentColor) and preserveAspectRatio="none" for the height-only stretch.

Docs

• README antiquity bullet lists the height comparator.
• llms.txt antiquity re-export list now names centimeter, inch, and foot.

Notes

• Heights are popularly-reported figures gathered for amusement, surfaced with a disclaimer; they are not independently verified, and historical heights especially are mythologized.
• demo/README.md is left untouched; it is broadly stale (still describes a two-kit ForgeBench/DemoSection/lib/kits.ts layout) and warrants its own cleanup rather than a one-line patch.

Testing

bun run check green (lib + demo build, biome, eslint, lib + demo typecheck, tests, knip, package). New demo-invariants cases cover the figures catalog (unique ids, in-domain heights, resolvable defaults). Section, stair-step, custom slider, color-coding, ancient readout, and the bench 100ths step verified by screenshot in a headless browser.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (b045897) to head (5cd453e).

Additional details and impacted files

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##              main       #49   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           34        34           
  Lines         2555      2555           
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  Hits          2555      2555           

Files with missing lines	Coverage Δ
src/kits/antiquity/index.ts	100.00% <100.00%> (ø)

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