fix(mcp): clarify API key fallback guidance

[pdurlej]

Summary

• document the actual MCP consult engine default path when engine is omitted
• add a ChatGPT browser-mode recovery hint to missing OpenAI API key errors for GPT models
• keep behavior unchanged: this does not add an engine:auto mode or silently switch engines

Fixes #171.

Tests

• pnpm vitest run tests/cli/runOracle/runOracle.logging.test.ts tests/mcp/consult.test.ts tests/mcp/utils.test.ts
• pnpm run format:check
• pnpm run lint
• pnpm run build
• pnpm test -- --no-file-parallelism --maxWorkers=1

Smoke

• Verified the missing-key session render now says to retry with --engine browser or MCP engine:"browser" / preset:"chatgpt-pro-heavy" for ChatGPT Pro subscription-backed browser mode.

[steipete]

Landed manually on main in eaf8499 as fix(mcp): clarify API key fallback guidance, with the changelog thanks in 7243cf6.

Verification:

• pnpm vitest run tests/cli/runOracle/runOracle.logging.test.ts tests/mcp/consult.test.ts tests/mcp/utils.test.ts ✅
• pnpm run check && pnpm run build ✅
• pnpm test ✅ (750 passed, 42 skipped)
• CI on main ✅ (Windows, Ubuntu, macOS)

Thanks @pdurlej.

[steipete]

Closing as landed on main in eaf8499. Thanks @pdurlej.