fix(search): map output sensitivity to content filter exit code

[renaissance04]

Search requests that return HTTP 200 with status_msg: "output new_sensitive"
were falling through to the generic "API error" path (exit code 1), so a
moderation block looked like an API/CLI failure.

mapApiError now detects output-side sensitivity and maps it to
ExitCode.CONTENT_FILTER (10) with a clear message.

Added a test case in test/errors/api.test.ts.

Fixes #234

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[renaissance04]

Follow-up: also detect the documented MiniMax status_code 1027
(output content sensitive), not just the "new_sensitive" text from
the report. The numeric code stays stable if the API changes the
message wording.