fix(links): repair broken external links flagged in #33

- learn/wallets.mdx: OKX wallet link 404'd (/wallet/sei retired) ->
  https://web3.okx.com/wallet/sei-evm (live Sei-EVM wallet page)
- lychee.toml: exclude false positives that hard-block the checker but
  serve real traffic — Sei's own RPC node endpoints (transient 503 from
  gateway rate-limiting) and updraft.cyfrin.io (Cloudflare 404 to bots)

Closes #33

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: alexander-sei

learn/wallets.mdx

@@ -40,7 +40,7 @@ different features and levels of security.
 | Dynamic | ✅ | Any | All | Embedded | ✅ | [Dynamic Wallet](https://dynamic.xyz) |
 | Privy | ✅ | Email / Social / Passkey / Wallet | 60 | Embedded | ✅ | [Privy](https://privy.io) |
 | Rabby | ✅ | Mnemonic / Priv/Passkey | 60 | Software | ✅ | [Rabby Wallet](https://chromewebstore.google.com/detail/rabby-wallet/acmacodkjbdgmoleebolmdjonilkdbch) |
-| OKX | ✅ | Mnemonic / Privkey | 118 / 60 | Software | ✅ | [OKX Wallet](https://web3.okx.com/wallet/sei) |
+| OKX | ✅ | Mnemonic / Privkey | 118 / 60 | Software | ✅ | [OKX Wallet](https://web3.okx.com/wallet/sei-evm) |
 | Gem Wallet | ✅ | Mnemonic / Privkey | 118 / 60 | Software | ✅ | [Gem Wallet](https://gemwallet.com/sei-wallet/) |
 
 Wallets with coin type 118 use the Cosmos HD derivation path; the same key still maps to a unique EVM `0x...` address via Sei's address-association system.

lychee.toml

@@ -45,9 +45,16 @@ exclude = [
   #   silostaking.io      → 402 Payment Required to bots
   #   dashboard.pimlico.io → 404 to bots (client-rendered app shell)
   #   blog.thirdweb.com   → cert chain rejected by lychee's TLS, fine in browsers
+  #   updraft.cyfrin.io   → 404 to bots (Cloudflare challenge), real 200 in browsers
   "^https?://(www\\.)?silostaking\\.io",
   "^https?://dashboard\\.pimlico\\.io",
   "^https?://blog\\.thirdweb\\.com",
+  "^https?://(www\\.)?updraft\\.cyfrin\\.io",
+  # Sei's own JSON-RPC / REST node endpoints (evm-rpc[-testnet|-arctic-1], rpc
+  # [-testnet]) intermittently answer the checker with a transient 503 from
+  # gateway rate-limiting, though they serve real traffic and are referenced
+  # 140+ times across the docs. Node liveness is monitored elsewhere.
+  "^https?://(evm-)?rpc(-testnet|-arctic-1)?\\.sei-apis\\.com",
 ]
 
 # Don't check mailto: links (this is the default; set explicitly for clarity).