Fix test_login_with_invalid_api_key leaking login thread

[delner]

Problem

Intermittent test failures with WebMock::NetConnectNotAllowedError and "terminated with exception" messages appearing during test runs.

Cause

test_login_with_invalid_api_key created a State without an org_id, which spawns a background login thread. When the VCR cassette was ejected after the test completed, the orphaned thread (still retrying with exponential backoff) would wake up and attempt a real HTTP request, triggering WebMock errors.

Solution

• Added minitest-stub_any_instance gem for instance method stubbing
• Created mock_login_in_thread test helper that:
  • Stubs login_in_thread to prevent background thread from spawning
  • Asserts the method would have been called
• Applied helper to the affected test

This follows the pattern established in PRs #65 and #68 for handling background thread isolation in tests.

[clutchski]

i think i'd just do blocking login in this case, vs adding new dependencies, mocks, etc. but approved, up to you.

[delner]

Removed the mock dependency, leveraged blocking_login and isolated other threaded tests in forks.