chore: update examples docs and deps

[phdargen]

Description

• Removes experimental nodeMiddleware and next canary instruction from docs which are no longer needed and have been removed from the examples implementation (https://github.com/coinbase/x402/pull/386).
• Use workspace:* references for all x402 packages
• Fixed ERC20 asset type casting in auth_based_pricing/backend.ts
• Aligned next version in fullstack/next example with other examples

Tests

• [x] Run pnpm build from /examples/typescript to verify all examples build successfully
• [x] Run pnpm test from the /typescript directory to ensure all tests pass

Checklist

• [x] I have formatted and linted my code
• [x] All new and existing tests pass
• [x] My commits are signed (required for merge) -- you may need to rebase if you initially pushed unsigned commits

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 1/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

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