[ninglinLiu]

Summary

Fixes four dead third-party links on Unichain pages (all currently return 404). These were not covered by #1177, which fixed the Optimism/Infura/QuickNode links.

Page	Old link (404)	New link
Unichain → Tools → Cross-chain (Polymer "documentation")	docs.polymerlabs.org/docs/build/interop-contract/	docs.polymerlabs.org/ (Polymer Docs home; the interop-contract page was removed when the docs moved to the Prove API)
Unichain → Tools → Cross-chain (Polymer "example implementations")	docs.polymerlabs.org/docs/category/examples-1	docs.polymerlabs.org/docs/category/examples (the "Examples" category)
Unichain → Tools → Account Abstraction (thirdweb Playground)	playground.thirdweb.com/connect/account-abstraction/connect	playground.thirdweb.com/account-abstraction (thirdweb Playground → Account Abstraction)
Unichain → Guides → Transfer USDC (footer "Developer Tools")	developers.circle.com/w3s/circle-programmable-wallets-an-overview	developers.circle.com/wallets ("Circle Wallets" overview)

Type of change

• Fix (typo, broken link, incorrect or outdated content)
• New content (guide, page, code example)
• Update to existing content
• Other

How has this been verified?

• curl -L returns 404 for all four old URLs and 200 for the new ones; checked the page titles/content ("Polymer Docs", "Examples | Polymer Docs", thirdweb Playground's Account Abstraction section, "Circle Wallets - Circle Docs").

Anything else reviewers should know?

Docs-only, 4 links on 3 lines in 3 files. Separate from #1173–#1178. Prepared with AI assistance; I reviewed the change and checked every link listed above.

[github-actions]

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[github-actions]

Reviewed the diff — this is a clean, narrowly-scoped change: 4 dead third-party links swapped for live replacements across 3 Unichain files, no code logic, contract addresses, or chain IDs touched. MDX/JSX syntax around each edited line is intact.

A couple of notes:

• I don't have outbound network access in this review environment, so I could not independently re-verify the new URLs' HTTP status myself. The PR description states all four old links 404 and all four new links return 200 with matching page titles — please have a human spot-check these before merge, per our policy of flagging any URL change for verification.
• Unrelated to this PR: content/unichain/tools/account-abstraction.mdx still has a https://developers.circle.com/w3s/gas-station link, which follows the same deprecated /w3s/... URL pattern as the Circle link being fixed here. Might be worth checking in a follow-up if it's also dead.

No other issues found — looks good otherwise.