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## Summary by cubic
Adds “Dyad Turbo” models for Pro users and centralizes model/provider
constants. Pro users can pick fast, cost‑effective models directly from
the ModelPicker, with clearer labels and gating.

- **New Features**
- Added Dyad Turbo provider in ModelPicker with Qwen3 Coder and Kimi K2
(Pro only).
- Turbo options are hidden for non‑Pro users; “Pro only” badge shown
where applicable.
- “Smart Auto” label now applies only to the Auto model to avoid
confusion.

- **Refactors**
- Moved all model/provider constants into language_model_constants.ts
and updated imports (helpers, client, thinking utils).

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