feat(console): expose AI SDK package in Zen models API

[Cretezy]

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

The Zen GET /v1/models response now includes an npm field for each model. The value is derived from the model's configured API format, matching the AI SDK packages documented for each Zen endpoint: Anthropic, Google, OpenAI, or OpenAI-compatible.

This is to match models.dev's API.

The shared response builder is used by both the full Zen model list and the Go model list, so both endpoints expose the same metadata shape.

How did you verify your code works?

• Ran bun typecheck from packages/console/app.
• Ran bun typecheck from packages/console/core.

Screenshots / recordings

Not applicable; this is an API response change.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

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