#23349 tests: register test_guard_hooks_from_base.py (base registry red)

#23316 added tests/test_guard_hooks_from_base.py without a tests/test-execution.toml entry. The registry check flags it on feat-cmux-next, and every branch's pre-commit hook adds the entry on its own, so open PRs keep conflicting with each other on the registry.

This adds only that entry, lane linux-guard: the test needs only Python, git and bash, and cmux-next.yml already runs it on Ubuntu in the checks job. Its sibling guard tests use the same lane, and it is the lane the validator suggests.

Tests

• scripts/ci/validate_test_execution_registry.py on this commit: the unregistered-test warning is gone.
• Unrelated, already on base: tests/test_media_auto_tour.py is registered twice. CI only warns about a duplicate that is already on base, and this PR leaves it alone.

No capture: test registry only.

Agent session: cosmic-gray

🤖 Generated with Claude Code

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Summary by cubic

Registers tests/test_guard_hooks_from_base.py in the test execution registry under the linux-guard lane so the unregistered-test check passes on feat-cmux-next.

#23316 added the test file without a tests/test-execution.toml entry. Since every branch's pre-commit hook adds its own entry, open PRs kept conflicting on the registry. This adds only that entry, matching the sibling guard tests and the lane the registry validator suggests; the cmux-next.yml checks job already runs the test on Ubuntu.