Replace manual _active_spinner + _pause_spinner/_resume_spinner with
_ThinkingSpinner class that owns the spinner lifecycle via __enter__/
__exit__ and provides a pause() context manager for temporarily
stopping the spinner during progress output.
Benefits:
- Restores Pythonic context manager pattern matching original code
- Eliminates duplicated start/stop boilerplate between single-message
and interactive modes
- pause() context manager guarantees resume even if print raises
- _active flag prevents post-teardown resume from async callbacks
The Rich console.status() spinner ('nanobot is thinking...') was not
cleared when tool call progress lines were printed during processing,
causing overlapping/garbled terminal output.
Replace the context-manager approach with explicit start/stop lifecycle:
- _pause_spinner() stops the spinner before any progress line is printed
- _resume_spinner() restarts it after printing
- Applied to both single-message mode (_cli_progress) and interactive
mode (_consume_outbound)
Closes#1956
Phase 1 _decide() now includes "Current date/time: YYYY-MM-DD HH:MM UTC"
in the user prompt and instructs the LLM to use it for time-aware scheduling.
Without this, the LLM defaults to 'run' for any task description regardless
of whether it is actually due, defeating Phase 1's pre-screening purpose.
Closes#1929
who96andXubin Ren