[Feedback]: Desktop lacks support for adding custom providers (parity with CLI `Add a provider`)

まず、issue で説明されている Desktop Settings または model-picker フローと CLI の「Add a provider」フローを比較します。これには、#25 に関連する provider 設定と session-sync の動作も含めます。既知の provider、カスタム provider ID、ベース URL、API キーをどのように表現するかを定義します。Linux 上で、要求された CLI 機能と同等に Desktop から provider を追加して再利用できれば完了です。

What problem are you trying to solve?

In Command Code Desktop (Linux, v0.1.30) there is no equivalent to the CLI v1.54.0 flow for adding custom providers (Add a provider / provider id: ollama, work-llm, openrouter… plus the list with vercel, groq, mistral, xai, together, cerebras, ↓ 184 more).

This is what the flow looks like in the CLI:

# Command Code v1.54.0
# models: muse-spark-1.3-contributor

Add a provider
Pick a known provider below, or type your own id.

provider id: ollama, work-llm, openrouter…
  vercel · https://ai-gateway.vercel.sh/v1
  groq · https://api.groq.com/openai/v1
  mistral · https://api.mistral.ai/v1
  xai · https://api.x.ai/v1
  together · https://api.together.xyz/v1
  cerebras · https://api.cerebras.ai/v1
  ↓ 184 more

In the Desktop app there is no screen/button/command (cmd) to do the same — only the default provider/login can be used, with no way to connect third-party providers (Ollama, OpenRouter, Groq, Together, etc.).

What would improve it?

Parity with the CLI in the Desktop app:

• An "Add a provider" screen/button in Settings (or in the model picker);
• A list of known providers plus a field for a custom provider id + baseURL + API key;
• The same 190+ providers available in the CLI.

What do you do today?

I use CLI v1.54.0 in the terminal to configure the provider, but the configuration is not reflected/reusable in the Desktop app on Linux — TUI/CLI and Desktop flows seem not to sync providers/sessions (related to #25).

Context / Environment

• Desktop: v0.1.30 (latest as of 2026-09-16), Linux
• CLI: v1.54.0 (muse-spark-1.3-contributor)
• Reported on: Linux