Show inline event type inference in the TypeScript guide

[mananbharti]

Summary

• Add a small inline onChange example to the DOM Events section.
• Explain that TypeScript infers React.ChangeEvent for its event parameter.
• Keep the existing extracted-handler example to show when an explicit event type is needed.

Testing

• yarn tsc passed.
• ESLint passed on src/content/learn/typescript.md.
• yarn test:eslint-local-rules passed.
• Heading ID checks passed.
• Type-checked the inline example with strict settings.
• Checked the DOM Events section in the local site preview.

Fixes #6752

[github-actions]

Size changes

Details

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