ci: skip terminus_harbor in test-envs

[mikasenghaas]

Summary

• Skip terminus_harbor environment in test-envs CI job since it uses prime-tunnel which is still experimental and has low usage limits

🤖 Generated with Claude Code

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Note

Low Risk
Test-only change that excludes one environment from CI; no production code or runtime behavior is modified.

Overview
Updates the test-envs CI checks to skip the terminus_harbor environment by adding it to SKIPPED_ENVS in tests/test_envs.py, since it depends on the experimental prime-tunnel with low usage limits.

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