test: isolate Qwen provider resolution from local pools

[crazyief]

Summary

• isolate the Qwen singleton credential resolver test from the higher-priority credential pool
• force an empty-pool precondition in the Qwen auto-fallthrough test
• keep both tests deterministic when the canonical runner preserves a developer's real HOME

Why

resolve_runtime_provider() correctly checks the credential pool before the singleton Qwen resolver. On machines with Qwen credentials under ~/.qwen, these tests can resolve the real pool entry instead of exercising their mocked resolver or auth-failure path.

The production priority is correct; the tests were missing the empty-pool precondition.

Test plan

• scripts/run_tests.sh -j 2 tests/hermes_cli/test_models.py tests/hermes_cli/test_runtime_provider_resolution.py -q --tb=short
• 235 tests passed, 0 failed on current origin/main
• git diff --check origin/main...HEAD

Scope

Test-only change. No runtime provider behavior is modified.

[teknium1]

Thanks for the focused test stabilization. Current main loads a credential pool before the Qwen singleton resolver (hermes_cli/runtime_provider.py:1695-1760), while Qwen CLI credentials are read from Path.home() / ".qwen" (hermes_cli/auth.py:2303-2316) and the shared fixture deliberately preserves HOME (tests/conftest.py:359-365). The two added empty-pool preconditions therefore exercise the intended mocked singleton and auto-fallthrough paths without changing production behavior.

Automated hermes-sweeper review.