docs: use auth interruption APIs in examples (#99698)
## Summary
- Replace generic `Unauthorized` and `Forbidden` errors with the stable
`unauthorized()` and `forbidden()` APIs across the mutating data, forms,
Server Actions, data security, and `use server` documentation.
- Distinguish unauthenticated requests from authenticated users who lack
permission in the security examples.
- Link to the API references and explain that the functions render the
matching fallback files.
This PR is stacked on #99696, which adds the complete pattern to the
error-handling guide.
## Verification
- `pnpm prettier --with-node-modules --ignore-path .prettierignore
--write docs/01-app/01-getting-started/07-mutating-data.mdx
docs/01-app/02-guides/data-security.mdx docs/01-app/02-guides/forms.mdx
docs/01-app/02-guides/server-actions.mdx
docs/01-app/03-api-reference/01-directives/use-server.mdx`
- `pnpm exec eslint --config eslint.config.mjs --fix
docs/01-app/01-getting-started/07-mutating-data.mdx
docs/01-app/02-guides/data-security.mdx docs/01-app/02-guides/forms.mdx
docs/01-app/02-guides/server-actions.mdx
docs/01-app/03-api-reference/01-directives/use-server.mdx`
- `NO_UPDATE_NOTIFIER=1 pnpm exec alex
docs/01-app/01-getting-started/07-mutating-data.mdx
docs/01-app/02-guides/data-security.mdx docs/01-app/02-guides/forms.mdx
docs/01-app/02-guides/server-actions.mdx
docs/01-app/03-api-reference/01-directives/use-server.mdx --quiet`
- Not run: framework tests (documentation-only change)
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