fix(ci): stabilize main test failures

[stephenschoettler]

Summary

• Re-export normalize_whatsapp_identifier from gateway.session for existing callers.
• Fix the remaining base test failures blocking the merge train across gateway shutdown, Slack tool progress routing, TUI session lifecycle, MCP dynamic refresh, CLI schema/auth expectations, and provider normalization.
• Harden shutdown and race tests so they assert the intended behavior without leaking background workers or pending typing tasks.

Test plan

• .venv/bin/python -m pytest -q -o addopts='' --tb=short -n auto $(tr '\n' ' ' < /tmp/pr17618_failed_tests.txt)
• .venv/bin/python -m pytest -q -o addopts='' --tb=short tests/gateway/test_gateway_shutdown.py tests/gateway/test_session_split_brain_11016.py tests/gateway/test_run_progress_topics.py tests/test_tui_gateway_server.py tests/tui_gateway/test_protocol.py
• .venv/bin/python -m pytest -q -o addopts='' --tb=short -n auto ...focused modified tests...
• .venv/bin/python -m compileall -q agent/anthropic_adapter.py gateway/platforms/base.py gateway/run.py hermes_cli/main.py hermes_cli/web_server.py tools/mcp_tool.py tui_gateway/server.py tests/hermes_cli/test_auth_commands.py tests/test_tui_gateway_server.py
• git diff --check

Notes

• This PR grew from the WhatsApp re-export into the minimal main-green patch set because the open merge train was blocked by shared base CI failures.
• A clean split branch was tested, but it failed on the existing WhatsApp import regression unless this PR's first commit was included. Keeping the fixes together here avoids a circular dependency.

[alt-glitch]

Likely duplicate of #17166 — same missing re-export of normalize_whatsapp_identifier from gateway.session.

[alt-glitch]

Likely duplicate of #17166 — same missing re-export of normalize_whatsapp_identifier from gateway.session.

[stephenschoettler]

Closing this one. The WhatsApp re-export portion is a duplicate of #17166, and the later CI stabilization changes broadened this beyond one logical change per CONTRIBUTING.md. If any of the CI fixes are still needed, I'll split them into a focused branch/PR from current main instead of keeping them bundled here.