Update llms summaries for new guides in PR #408.

Adds links for:
- Base Account: Advanced Authentication Patterns (MFA, sessions, enterprise SSO)
- Cookbook: Build Cross-Chain Applications (multi-chain architecture, bridging, messaging)

Ensures LLMs summaries reflect newly added significant docs.

Author: cursoragent

docs/base-account/llms-full.txt

@@ -34,6 +34,7 @@ const { status } = await getPaymentStatus({ id })
 - [Authenticate Users](https://docs.base.org/base-account/guides/authenticate-users.md) — SIWE + ERC‑6492
 - [Advanced Authentication Patterns](https://docs.base.org/base-account/guides/advanced-authentication.md) — MFA, TOTP, sessions, cross‑device sync
 - [Accept Payments](https://docs.base.org/base-account/guides/accept-payments.md) — Base Pay
+- [Advanced Authentication Patterns](https://docs.base.org/base-account/guides/advanced-authentication.mdx) — MFA, session tokens, SAML/OIDC, device sync
 - [Batch Transactions](https://docs.base.org/base-account/improve-ux/batch-transactions.md) — Multi‑call
 - [Paymasters](https://docs.base.org/base-account/improve-ux/sponsor-gas/paymasters.md) — Sponsor gas
 - [ERC‑20 Paymasters](https://docs.base.org/base-account/improve-ux/sponsor-gas/erc20-paymasters.md) — ERC‑20 gas

docs/base-account/llms.txt

@@ -15,6 +15,7 @@
 - [Authenticate Users](https://docs.base.org/base-account/guides/authenticate-users.md) — SIWE with ERC‑6492 signatures
 - [Advanced Authentication Patterns](https://docs.base.org/base-account/guides/advanced-authentication.md) — MFA, TOTP, sessions, cross‑device sync
 - [Accept Payments](https://docs.base.org/base-account/guides/accept-payments.md) — One‑tap USDC payments with Base Pay
+- [Advanced Authentication Patterns](https://docs.base.org/base-account/guides/advanced-authentication.mdx) — MFA, session management, enterprise SSO
 
 ## Framework Integrations
 - [Wagmi: Setup](https://docs.base.org/base-account/framework-integrations/wagmi/setup.md) — Configure connectors and chains

docs/cookbook/llms-full.txt

@@ -23,6 +23,7 @@
 - [Go Gasless](https://docs.base.org/cookbook/go-gasless.md) — Sponsor gas
 - [Base App Coins](https://docs.base.org/cookbook/base-app-coins.md) — Coins in Base App
 - [Testing Onchain Apps](https://docs.base.org/cookbook/testing-onchain-apps.md) — Testing strategies
+- [Build Cross-Chain Applications](https://docs.base.org/cookbook/build-cross-chain-apps.mdx) — Multi-chain architecture, bridging, messaging
 
 ### Build with AI
 - [AI Prompting](https://docs.base.org/cookbook/ai-prompting.md) — Prompt patterns

docs/cookbook/llms.txt

@@ -16,6 +16,7 @@
 - [Go Gasless](https://docs.base.org/cookbook/go-gasless.md) — Sponsor user gas
 - [Base App Coins](https://docs.base.org/cookbook/base-app-coins.md) — Coins in Base App
 - [Testing Onchain Apps](https://docs.base.org/cookbook/testing-onchain-apps.md) — Testing strategies
+- [Build Cross-Chain Applications](https://docs.base.org/cookbook/build-cross-chain-apps.mdx) — Multi-chain architecture, bridging, messaging
 
 ## Build with AI
 - [AI Prompting](https://docs.base.org/cookbook/ai-prompting.md) — Prompt patterns