fix(opencode): install openai websocket fetch for configured keys

[Chikage0o0]

Issue for this PR

Fixes #29843

Type of change

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

What does this PR do?

Installs the OpenAI plugin WebSocket fetch when API auth comes from provider config (provider.openai.options.apiKey) or env (OPENAI_API_KEY) and no stored auth entry exists. The previous loader only ran when auth.get("openai") returned saved auth, so configured keys could build the provider but miss the WebSocket fetch needed for Responses/WebSocket calls.

Stored OpenAI auth still takes precedence when present, preserving opencode auth login openai behavior.

How did you verify your code works?

• bun test test/provider/provider.test.ts --timeout 30000
• bun typecheck
• pre-push hook: bun turbo typecheck

Screenshots / recordings

N/A — not a UI change.

Checklist

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

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[github-actions]

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