assets: add typographic explainer gallery (2026 v4)

Instrument Serif display, Instrument Sans UI, Geist Mono labels, all
vendored as woff2 and inlined at render time so output no longer depends
on locally installed fonts (Inter never was — it fell back to SF Pro).
Drops the corner wordmark along with the icon; the hero keeps a small
mono kicker.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: esokullu

assets/webstore-explainer-2026-4/01-hero-light.png

@@ -0,0 +1,47 @@
+# Web Store explainer visuals 2026 — v4 (typographic)
+
+Same gallery and copy as v3 (`../webstore-explainer-2026-3`), retypeset. No product
+icon and no "WebBrain" corner wordmark on any slide — the Web Store shows both beside
+the listing. The hero keeps a small mono "WEBBRAIN" kicker as the only brand mark.
+
+Type system:
+- Display (headlines, prices, stat numerals) — **Instrument Serif** 400
+- UI (body, subs, panel text) — **Instrument Sans** 400–700
+- Labels (eyebrows, chips, URLs, buttons) — **Geist Mono** 600, uppercase, wide tracking
+
+Fonts are vendored in `fonts/` and inlined as base64 at render time, so output no longer
+depends on what is installed locally. All three are OFL 1.1; license texts sit beside them
+in `fonts/OFL-*.txt` and must stay with the binaries. Latin subsets only, 68 KB total.
+
+The mock agent panel on 02 still reads "WebBrain is acting" — that is depicted product UI,
+not slide branding. Say so if you want it neutralised too.
+
+v2/v3 are untouched and still use the old sans stack; the four versions are independent
+copies, so a copy change needs applying in each.
+
+Files (1280×800):
+- 01-hero.png: Mono kicker + serif tagline hero
+- 02-tell-the-browser.png: Flight-search command front and center as chat input, browser acting on it
+- 03-ask-any-page.png: Ask mode, cropped to the answer panel
+- 04-any-llm.png: Model picker, cropped to the provider dropdown
+- 05-plan-before-act.png: Plan review with Approve/Adjust before actions run
+- 06-launch-offer.png: WebBrain Cloud $5/mo (reg. $8), Save 35%
+- 07-social-proof.png: 500+ GitHub stars, 20+ contributors, MIT — repo bar with contributor avatars
+
+Light-background alternates of the two dark slides (originals kept, use whichever fits the gallery):
+- 01-hero-light.png
+- 05-plan-before-act-light.png
+
+Both come from the same `hero(light)` / `planScene(light)` functions, so edits apply to
+dark and light together. In the light plan card the panel goes white and the accent green
+darkens for contrast against white button text.
+
+Star/contributor counts are hardcoded in `proofScene()`; bump them there when they go stale (544 stars at last render, 2026-07-29). The avatar initials are decorative, not real contributor handles.
+
+Slide 07 is appended after the offer to keep the existing filenames stable. If proof-then-price reads better, swap the last two entries in the `scenes` array and rename the two PNGs.
+
+Regenerate:
+
+```bash
+node assets/webstore-explainer-2026-4/render.mjs
+```