docs(partners): link provider address catalogs instead of hardcoding partner contract addresses

[GigaHierz]

The hole, and the fix

Partner contract addresses hardcoded in our pages rot invisibly — nothing watches on-chain activity. Verified via Blockscout on 2026-08-24: the Witnet price-feed proxy we list (0x1111AbA2…) has been quiet on mainnet since 2026-01-23 while another WitnetProxy (0x3210564c…) has posted daily since and is active today; of the two Witnet randomness contracts, the newer WitRandomnessV3's last recorded tx (2026-02-27) predates WitnetRandomnessV2's (2026-04-22) — which one is canonical is the provider's call, not ours. Both benchmarked docs sets already avoid this class of bug: Optimism's oracles page links each provider's own address catalog; Base lists no partner addresses at all. Our Chainlink / RedStone / Supra / DIA / Quex pages already carry zero addresses — Witnet and Band were the outliers.

Changes (3 of the 6 pages inventoried in #2277 needed edits):

• tooling/oracles/wit-oracle.mdx — both address blocks (price-feed proxy incl. the hardcoded address in the code sample, and randomness) replaced with links to Witnet's canonical pages (Celo price feeds, randomness contract addresses, feeds.witnet.io/celo — all returned 200 today). The retired-Alfajores bullets went with them.
• tooling/oracles/band-protocol.mdx — the two inline literals dropped; the text already told readers to check Band's page for the current address, now it only does that.
• build-on-celo/build-with-farcaster.mdx — the swap example's router 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D is Ethereum's Uniswap V2 router; eth_getCode on Celo mainnet returns 0 bytes, so the example as written could not work. Replaced with a placeholder + link to Uniswap contracts on Celo and a Warning that the ABI must match a router actually deployed on Celo (v3/v4). The two Anvil test recipients are now labelled // example recipient — replace.

Reviewed, deliberately unchanged (the other 3 pages from the inventory): build-with-usat.mdx (USA₮ token 0xD2ab… + adapter 0x0357… are Celo fee-allowlist entries; the adapter was verified in the on-chain FeeCurrencyDirectory in #2273's evidence), nightfall.mdx (CELO token-duality address, Sepolia USD₮ matching fee-currencies.mdx:74, and a clearly-scoped example variable), ledger/to-celo-cli.mdx (0x…0001 test recipient in a test command).

The policy sentence itself ("partner addresses live with the provider; Celo-core tables stay; example addresses are labelled") is added to AGENTS.md as a commit on #2269, where that file is already under review.

What this does NOT do / residual risk

• Readers now leave our docs for the address — deliberate: the provider's page is the only one that stays correct.
• Does not verify Band's current addresses (we no longer state any); does not touch the stale Witnet pair in prose anywhere else (grep: none outside legacy/).
• The Farcaster swap example remains v2-shaped; making it a runnable v3 example is content work for story: Agent-experience pass — first-mile wallet page, x402 polish, troubleshooting examples, discoverability research #2263, not this fix.
• No automated address/activity check added (noted as freshness-workstream material in task: Stop hardcoding partner contract addresses — link to provider docs; fix the six pages that carry them (Witnet feeds went quiet) #2277).
• wit-oracle.mdx is currently orphaned from nav; task: Orphaned-pages audit — re-nav or delete the 22 pages on disk that are missing from navigation #2253 re-navs it after this lands (note already on the sheet/issue).

Judgement calls

• Kept the Witnet and Band pages themselves (Optimism pattern: provider pages, addresses linked) rather than Base's no-page pattern — deleting pages is task: Orphaned-pages audit — re-nav or delete the 22 pages on disk that are missing from navigation #2253/story: Build tab — merge "Build on Celo" and Tooling into build/*, with Agents and Mini Apps leading #2259 territory.
• Placeholder string ("0xYourSwapRouterAddress") over picking a router for the reader: choosing v3 SwapRouter02 would silently break with the v2 ABI in the same snippet. Reversible either way.

Issues

Refs #2277 — closes the three-page fix and the three-page review; the AGENTS.md box closes when #2269 merges; the "#2253 waits" note is already posted.

Stacking / conflicts

Branched off main, independent of my other open PRs (none touches these three files). The AGENTS.md policy commit rides on #2269.

Verification evidence

Blockscout api/v2, 2026-08-24:
0x1111AbA2… WitnetProxy        last tx 2026-01-23   (the address we listed)
0x3210564c… WitnetProxy        last tx 2026-08-24   (active; not listed by us)
0xC0FFEE98… WitnetRandomnessV2 last tx 2026-04-22
0xc0ffee69… WitRandomnessV3    last tx 2026-02-27
eth_getCode 0x7a250d…88D on https://forno.celo.org -> 0 bytes
$ grep -rn '0x1111AbA2\|0xC0FFEE98\|0x8c064bCf\|0xDA7a001b\|0x7a250d56' <the three pages>
(none)
$ mint broken-links   # on e3eed36d
success no broken links found

All five provider-catalog URLs linked returned 200 today.

Remaining ops steps

• none

Checklist

• Title is the commit message I want on main
• Every claim above measured (Blockscout / eth_getCode / curl), commands in evidence
• mint broken-links passes
• Judgement calls flagged above
• No secrets in the diff