* fix(ibus): raise exception on setup failure to enable fallback
- Add IBusSetupError exception class for detailed error context
- Modify _setup_engine() to raise exception instead of silent return
- Ensures text_injector.py fallback mechanism works when IBus fails
- Add unit tests for IBusSetupError and setup failure scenarios
Fixes silent IBus text injection failures on Wayland/Fedora reported in #34
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
* test(text-injector): add tests for IBus setup failure fallback
- Test that TextInjector falls back to xdotool when IBus fails
- Test fallback on both X11 and Wayland environments
- Test that text injection still works after IBus failure
Related to #34
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
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Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
