Parthenon example + environment, glyphcss shadow fix, per-page social cards

[apresmoi]

A walkable Parthenon example, plus a few things that grew out of building it.

Parthenon example (/examples/parthenon)

• Procedural octastyle Doric temple (crepidoma, 8×17 colonnade, entablature, pediments, walkable interior with naos colonnade + golden Athena) rendered as ASCII with green Matrix rain.
• Orbit by default, FPV walkthrough (WASD/jump, pointer-lock, step-climb + column collision).
• Two styles: matrix (green rain) and marble (realistic stone).
• Marble environment: skydome + world-anchored drifting clouds, grass ground, hazy hills, a sun disc, and a single sun azimuth/height control that drives the directional light, the sun, and the shadow direction together. Sky/clouds/ground/hills toggles + cloud size/cover/drift sliders.
• Self + cast shadows on the temple and floor.
• The entire sidebar (incl. FPV position/look and env state) is packed into a tiny base64url URL hash so any view is shareable.

glyphcss (core)

• fix(glyphcss): perspective-correct shadow interpolation. Shadow light-space (u,v,depth) were interpolated affinely (screen-space) instead of perspective-correctly, so shadows warped under a perspective camera and shifted with the camera (worst up close in FPV). Now matches the world-position/UV/texture paths. Benefits every perspective-camera shadow scene (gallery included). New regression test; all tests pass.

@glyphcss/effects

• Matrix rain monochrome now lights a bright head and fades the tail (the classic head→tail gradient) instead of one flat green. Tests + docs updated.

Website

• Per-page ASCII social-preview cards via a shared <BaseHead> — each page (synth, wordart, gallery, all examples) gets an Open Graph/Twitter card that is a real glyphcss ASCII render of that page (generated by scripts/generate-og.mjs). Fixes the missing/duplicate meta across pages.

pnpm test && pnpm build green across the monorepo.