* fix(telemetry): skip signal handler registration in non-main threads
When CrewAI is initialized from a non-main thread (e.g. Streamlit, Flask,
Django, Jupyter), the telemetry module attempted to register signal handlers
which only work in the main thread. This caused multiple noisy ValueError
tracebacks to be printed to stderr, confusing users even though the errors
were caught and non-fatal.
Check `threading.current_thread() is not threading.main_thread()` before
attempting signal registration, and skip silently with a debug-level log
message instead of printing full tracebacks.
Fixes crewAIInc/crewAI#4289
* fix(test): move Telemetry() inside signal.signal mock context
Refs: #4649
* fix(telemetry): move signal.signal mock inside thread to wrap Telemetry() construction
The patch context now activates inside init_in_thread so the mock
is guaranteed to be active before and during Telemetry.__init__,
addressing the Copilot review feedback.
Refs: #4289
* fix(test): mock logger.debug instead of capsys for deterministic assertion
Replace signal.signal-only mock with combined logger + signal mock.
Assert logger.debug was called with the skip message and signal.signal
was never invoked from the non-main thread.
Refs: #4289