Fix published Oxlint plugin entrypoints

[SandroMaglione]

Summary

• Publish the plugin root and recommended configuration from built JavaScript and declarations.
• Exercise the raw npm pack path in the consumer smoke test so source entrypoints cannot be published again.
• Add a patch changeset; the fixed package group will release all three packages at 0.26.1.

Changeset

• Added or updated for a library or package-metadata change
• Not required because this PR does not change a publishable package

Validation

• pnpm check
• Automated type-performance measurement passed or was not required
• Automated runtime- and memory-performance measurement passed or was not required

Local functional smoke tests also passed with pnpm perf:types and pnpm perf:runtime. The pull request workflows classified the package-metadata and release-test change as not requiring base-versus-PR measurement.