* fix(ibus): wait for engine readiness before first injection
Add a startup readiness probe that pings the IBus engine after activation so first-use dictation no longer races do_enable(). Also switch NO_ENGINE retry behavior to exponential backoff and cover the new flow in tests.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
* test(ibus): cover readiness probe edge cases
Add focused tests for the new startup readiness path, including direct PING success, retry exhaustion, unexpected responses, and engine re-activation before injection. This raises coverage on vocalinux.text_injection.ibus_engine from 68% to 73% in the targeted suite.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
* fix(text-injection): avoid blocking IBus and clipboard fallbacks
Warm IBus in the background so startup no longer stalls while readiness probing, and make clipboard helpers fail fast with per-session health caching so non-ASCII ydotool fallback does not lock dictation.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
* test(ibus): update retry tests for merged NO_ENGINE recovery logic
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Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
