feat(cli): add TUI custom provider setup

[yanzhanglee]

Issue for this PR

Closes #

Type of change

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

What does this PR do?

Adds custom provider setup to the TUI provider picker. The new flow configures an OpenAI-compatible endpoint by collecting a provider ID, display name, base URL, optional API key or env var reference, models, and optional headers.

The saved config uses the same provider shape as the WebUI custom provider flow, then refreshes provider state and opens model selection for the new provider.

How did you verify your code works?

• npx --yes [email protected] --cwd packages/opencode test src/cli/cmd/tui/component/dialog-custom-provider-form.test.ts --timeout 30000
• npx --yes [email protected] run --cwd packages/opencode typecheck

Screenshots / recordings

Not included. This is a TUI dialog flow and was verified with unit coverage for the generated provider config plus typecheck.

Checklist

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

[github-actions]

Hey! Your PR title [codex] Add TUI custom provider setup doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search, I found a potentially related PR:

PR #18550: "feat: manage custom providers within model settings"
#18550

This PR appears to be related as it also deals with managing custom providers. However, the current PR (25112) specifically focuses on adding a TUI (terminal UI) custom provider setup dialog for configuring OpenAI-compatible endpoints, which seems to be a more recent/specific implementation compared to the earlier PR.

All other results are related to provider support in general but don't appear to be duplicates of the specific TUI custom provider form feature being added in PR #25112.

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍