* fix(threading): harden thread safety for HTTP session, IBus, and text injector
Four critical thread-safety fixes identified during PR #335 review:
1. Remote API: snapshot _http_session under _model_lock in
_process_audio_buffer() to prevent use-after-close races with
reconfigure/reinitialize. Pass session as explicit parameter to
_transcribe_with_remote_api, _try_whispercpp_server_api, and
_try_openai_api. Call _http_session.close() before setting to None
in reinitialize_after_resume(). Remove blocking connection probe
from _init_remote_api() (settings dialog has a Test Connection
button for that).
2. Text injector: extend _state_lock to protect stop() (writes
_ibus_injector=None and _ibus_ready=False) and inject_text() reads
of environment/_ibus_injector. Also guard environment/wayland_tool
writes in _switch_to_non_ibus_backend() and WAYLAND_XDOTOOL fallback
in inject_text's exception handler.
3. IBus engine: snapshot cls._active_instance into a local variable
before the do_inject closure in the socket server handler, closing
the TOCTOU race with do_destroy().
4. Test suspend handler: add _http_session=None to _make_manager()
fixture so reinitialize_after_resume() finds the attribute.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
* test(threading): update tests for thread-safety changes
- test_recognition_manager_remote_api: pass session param to
_transcribe_with_remote_api, _try_openai_api, and
_try_whispercpp_server_api. Update assert_called_once_with patterns
for the new session argument. Simplify init tests that no longer
need connection probe mocks (removed from _init_remote_api).
- test_text_injector: add threading.Lock to all TextInjector.__new__()
instances so _state_lock is available for lock-guarded methods.
- test_suspend_handler: add _http_session=None to _make_manager()
fixture so reinitialize_after_resume() finds the attribute.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
* test(threading): improve coverage for thread-safety fixes
Add tests for _process_audio_buffer remote API dispatch (session snapshot
under lock, early return when session is None) and reinitialize_after_resume
session close. Mark server_thread as pragma: no cover (blocked by conftest
to prevent CI hangs).
