feat(seo): inject brand-level Organization JSON-LD with sameAs linking docs to the Celo entity

[GigaHierz]

The hole, and the fix

Verified live today: Mintlify auto-injects an Organization schema named "Celo Docs" with no sameAs, plus a WebSite node crediting Mintlify as creator — the docs are disconnected from the Celo brand entity that search and AI engines resolve.

Adds seo-schema.js (Mintlify loads any content-directory .js on every page, no wiring needed) injecting one JSON-LD @graph: an Organization Celo (https://celo.org/#organization) with a sameAs array (GitHub org, X, YouTube, Discord, Forum, CoinGecko, DefiLlama, L2BEAT), and a WebSite node for docs.celo.org whose publisher points at that Organization — the docs→brand linkage the entity graph was missing.

What this does NOT do / residual risk

• Client-side injection: the script runs after load. Google and DOM-rendering crawlers process it; plain-fetch crawlers see only Mintlify's static blocks. Static head injection is not available on the current plan — recorded in the file header.
• Does not touch celo.org's own missing JSON-LD (Framer; tracked outside this repo) and cannot rename Mintlify's auto-generated "Celo Docs" nodes.
• Duplicate-node risk is low: the injected @ids (celo.org/#organization, docs.celo.org/#celo-docs) differ from Mintlify's (docs.celo.org/#organization, docs.celo.org#website).

Judgement calls

• sameAs list = the docs.json footer socials + the three data aggregators the entity graph needs (CoinGecko, DefiLlama, L2BEAT). Adding/removing an entry is a one-line change.
• Logo reuses the docs logo asset; swap to a brand asset URL if marketing prefers.

Issues

Refs #2283 — closes the script box; the "verified on the preview deployment" box stays open until the Mintlify preview for this PR is up (checkbox below).

Stacking / conflicts

Branched off main, independent — new file only.

Verification evidence

# live, before this change:
$ curl -sL https://docs.celo.org/ | grep ld+json   # Organization name "Celo Docs", no sameAs; WebSite creator = Mintlify
# this branch:
$ node -e "…"    # script parses; the JSON-LD object serializes cleanly
$ mint broken-links   # on 8b7a63ef
success no broken links found

Every sameAs URL verified: five return 200 to curl; CoinGecko and DefiLlama return 403 to curl (Cloudflare bot-blocking) but their APIs confirm the slugs (api.coingecko.com/api/v3/coins/celo → id celo; api.llama.fi/v2/chains lists Celo); L2BEAT project page returns 200.

Remaining ops steps

• Once the Mintlify preview deploys for this PR, open any page, run JSON.parse(document.querySelectorAll('script[type="application/ld+json"]')[last].text) in the console (or Google's Rich Results test) and tick this box

Checklist

• Title is the commit message I want on main
• Script syntax-checked; JSON-LD validated locally; all entity URLs verified
• Known limitation (client-side injection) stated in file and above
• No secrets in the diff