feat: swap the hero portrait for the skyline illustration

[dommango]

Summary

Replaces the hero headshot with the hand-drawn NYC-skyline portrait, and removes the old cartoon.

The new art couldn't just be dropped into the old slot. The hero cropped its image to a square (width={320} height={320} plus aspect-ratio: 1/1; object-fit: cover). The drawn frame is part of this artwork, so a centre crop of the 1024×1536 source cut the frame's top and bottom edges and clipped the top of the head — the old cartoon only survived that because it had no frame. So the portrait now renders at its full 2:3: the box goes 320×320 → 320×480 and the hero row grows ~160px, with the text column still centred beside it (align-items: center on .hero-head).

Also drops a 3.4MB file that was shipping for nothing. portrait_skyline.png was already committed but referenced nowhere — and under output: 'export', everything in public/ is copied to out/ and deployed regardless. This ships a 640px-wide WebP derivative instead (2× the ~300px display box).

Encoding note: lossy beat lossless badly here. Dense cross-hatching is high-entropy, so lossless WebP came out at 733KB vs 171KB for q80 — worth knowing if this art is ever re-exported. I compared q80 against the master at true display size and there's no visible difference. Net 3.4MB → 171KB, which is also smaller than the 244KB cartoon it replaces.

	before	after
shipped bytes	3.4MB PNG + 244KB JPG	171KB WebP
hero portrait	320×320, cropped	320×480, whole

Test plan

• npx tsc --noEmit — clean
• npm run build — static export succeeds
• npx playwright test — 20/20 (the no-horizontal-overflow matrix covers the taller hero)
• out/images/ contains only portrait-skyline.webp — both PNGs gone
• Rendered ratio measured at 0.667 (2:3, i.e. uncropped) at both 1440px and 390px
• Screenshotted at 1440px and 390px: frame intact top and bottom, head not clipped, caption still reads correctly
• q80 compared against the 3.4MB master at true 300px display size — indistinguishable

Note

Deleting cartoon-headshot.jpg removes it from the working tree, not from history — same distinction as any deleted file. Nothing sensitive here, no action needed.