feat(app): match the TUI integration dialog in desktop - #56106

The desktop connect dialog now follows the TUI's DialogIntegration, which is the reference behavior.

What changed

Integration list

• The title is "Connect an integration". Groups are MCP first, then Popular (Console, Go, OpenAI, GitHub Copilot, Anthropic, Google; the TUI now lists Console before Go as well), then Services.
• Each connected row shows its account label, or "N connections", with a check.
• A connection that needs a fresh sign-in shows Sign in required →.
• Integrations that only read environment variables are disabled and labelled "Environment only".
• The Recommended badges and taglines are gone, because the TUI doesn't have them. The "Custom OpenAI-compatible provider" entry stays.

Methods

• OpenCode Go connects with its own methods (an API key), the same as the TUI. Choosing it no longer starts the Console sign-in.
• OpenCode Console lists its real methods ("OpenCode Console account", "API key (service account)") in the same list every integration uses. The device-code view after sign-in hasn't changed.
• Methods follow the TUI's order: sign-ins first, API keys last. The "Browser" hint that showed on API keys is gone.
• command methods (for example well-known auth.command logins) now run. The dialog streams their output while it waits. Before, they were dropped and a fake API key form appeared instead.
• An integration with no interactive methods no longer gets that fake API key form.

Auth forms

• Fields are asked one at a time, like the TUI, so when conditions see every earlier answer.
• These field types now work: string choices with "type your own answer", yes/no, multiselect (with custom values and min/max), number and integer, and external "Open link, then I finished" steps.
• Before, any field that wasn't a string made the method fail with "unsupported fields".

Accounts

• "Add account" is the first row, as in the TUI.
• An account that needs a sign-in shows "Sign in required" on its row. Selecting it opens its link or starts a new sign-in.
• Removing the last account disconnects the integration and closes the dialog.

After connecting

• Every connection, including a second account, shows a toast and then that provider's model choice. Before, only the very first connection did this.
• When the dialog is opened from the composer (model picker, unpaid dialog, /connect), the chosen model applies to that composer instead of opening a new draft tab.
• MCP integrations close the dialog instead, because they have no models.
• The desktop model picker now has a "Connect an integration" item, like the TUI's model dialog.

The English copy changed in two places: command.provider.connect is now "Connect an integration" and dialog.provider.accounts.add is now "Add account". New keys are English only. Keys that are no longer used were removed from every locale.

Demo

https://github.com/anomalyco/opencode/releases/download/pr-56106-video/desktop-integration-dialog-tui-parity.mp4

This was recorded from this branch's real desktop dev build (packages/desktop, bun dev) under Xvfb, with an isolated home.

The demo-only data has two parts:

• A local plugin adds "Acme" integrations so a command login, every form field type, an expired sign-in and an environment-only integration are visible.
• The API keys are fake.

Checks

• bun typecheck passes in packages/app.
• The unit tests pass: providers, settings, runtime and composer, 389 tests.
• oxlint (including the anti-slop rules) and prettier are clean on the changed files.
• E2E: the provider tests in settings.spec.ts were updated for the new behavior.
  • Locally, the new Console method-list, Go key, lone-method and add-Console-account tests pass.
  • Three provider tests that use function-valued integration fixtures fail the same way on origin/dev locally: the mock /api/integration returns 500 in this environment.
  • The mobile picker tests also fail locally on origin/dev.
  • CI should decide those.

Requested by: @thdxr (dax via Slack)