docs.json contains redirects to non-existent internal destinations

## Summary

[docs/docs.json](cci:7://file:///C:/Users/Zeki/CascadeProjects/base-docs-research/docs/docs.json:0:0-0:0) appears to contain multiple redirects whose internal destinations do not exist in the current docs source.

## Examples

### `/get-started/migrate-from-onchainkit`

Many OnchainKit redirects point to this destination, but I could not find a corresponding docs page.

Example lines:

- `docs/docs.json:1261`
- `docs/docs.json:1265`
- `docs/docs.json:1269`
- `docs/docs.json:1273`

### `/base-account/basenames/basenames-wagmi-tutorial`

Several Basenames redirects point to this destination, but `docs/base-account/basenames/` currently only contains:

- [basename-transfer.mdx](cci:7://file:///C:/Users/Zeki/CascadeProjects/base-docs-research/docs/base-account/basenames/basename-transfer.mdx:0:0-0:0)
- [basenames-faq.mdx](cci:7://file:///C:/Users/Zeki/CascadeProjects/base-docs-research/docs/base-account/basenames/basenames-faq.mdx:0:0-0:0)

Example lines:

- `docs/docs.json:1101`
- `docs/docs.json:1105`
- `docs/docs.json:1109`

### `/apps/quickstart/create-new-app`

This route does not appear to exist. The current Apps quickstart page seems to be:

`/apps/quickstart/build-app`

Example lines:

- `docs/docs.json:1785`
- `docs/docs.json:2149`
- `docs/docs.json:2153`

### `/ai-agents/payments/x402-protocol`

Referenced at:

- `docs/docs.json:3045`

But the current payment pages appear to be:

- [ai-agents/payments/pay-for-services-with-x402.mdx](cci:7://file:///C:/Users/Zeki/CascadeProjects/base-docs-research/docs/ai-agents/payments/pay-for-services-with-x402.mdx:0:0-0:0)
- [ai-agents/payments/accepting-payments.mdx](cci:7://file:///C:/Users/Zeki/CascadeProjects/base-docs-research/docs/ai-agents/payments/accepting-payments.mdx:0:0-0:0)

## Expected behavior

All internal redirect destinations should resolve to existing docs routes.

## Suggested fix

Audit [docs.json](cci:7://file:///C:/Users/Zeki/CascadeProjects/base-docs-research/docs/docs.json:0:0-0:0) redirects and update stale destinations to current route names, or restore the missing destination pages where appropriate.

## Impact

Broken migration redirects can send users from old docs URLs to 404 pages, especially after docs restructures.