fix(gateway): strip internal tool-trace banners from chat output

[ooiuuii]

Summary

• add a shared user-visible text sanitizer for internal tool-trace banner lines, for example:

\u26a0\ufe0f \U0001f6e0\ufe0f `search repos (agent)` failed

• apply it to chat final-response/status sanitization while preserving raw programmatic surfaces
• apply the same cleanup to GatewayStreamConsumer._clean_for_display() so streamed chat text gets the same backstop

Context

This ports the same outbound boundary covered by OpenClaw's recent Slack/Matrix fixes:

• fix(slack): sanitize internal tool-trace lines from outbound text openclaw/openclaw#97367
• fix(matrix): sanitize internal tool-trace lines from outbound text openclaw/openclaw#97372

Fixes #54957.

Duplicate Audit

Related but not a duplicate of #38732: that PR blocks stale commentary after final delivery and fixes a Telegram duplicate-send path. This PR is a narrower outbound sanitizer for already-assembled chat text that contains internal tool-trace banner lines, and it applies to final responses, status messages, and streaming display cleanup across chat surfaces while preserving raw local/API/webhook diagnostics.

Also adjacent to #30574, #53334, and #54865, but those cover compression/status/error/runtime notices. This PR only strips the internal tool-trace banner shape shown above.

Tests

• TMP=.tmp-pytest TEMP=.tmp-pytest TMPDIR=.tmp-pytest .\.venv\Scripts\python.exe -m pytest tests/gateway/test_telegram_noise_filter.py tests/gateway/test_stream_consumer.py -q (325 passed)
• TMP=.tmp-pytest TEMP=.tmp-pytest TMPDIR=.tmp-pytest .\.venv\Scripts\python.exe -m ruff check gateway/platforms/base.py gateway/run.py gateway/stream_consumer.py tests/gateway/test_telegram_noise_filter.py tests/gateway/test_stream_consumer.py
• git diff --check

[teknium1]

Thanks for covering both final and streamed output paths. The premise is still present on current main: gateway/run.py:434 only redacts secrets before returning final chat text, and gateway/stream_consumer.py:1647 reaches BasePlatformAdapter.strip_media_directives_for_display(), whose current implementation at gateway/platforms/base.py:3710-3718 only handles media directives.

Problems

• gateway/run.py:445 adds banner stripping to _prepare_gateway_status_message(), but the PR adds no direct test for that status-delivery path. tests/gateway/test_telegram_noise_filter.py covers final responses; tests/gateway/test_stream_consumer.py covers streamed display.

Suggested changes

• Add a status-helper regression test for a chat platform and a raw platform, using the same banner fixture and raw-surface contract as the final-response tests.

Automated hermes-sweeper review.

[teknium1]

This adds a third sanitization boundary, but the new tests cover only final responses and streamed display. Please add a direct _prepare_gateway_status_message() regression test for both a chat surface and a raw surface.