v0.6.1

docker-talkies v0.6.1 — fix qwen3-tts kwarg regression from v0.6.0.

Patch release. v0.6.0 shipped PR #1's Qwen3-TTS instructions
wiring + x-vector fallback with a wrong kwarg name on
`model.generate_voice_clone(...)` — every Qwen3 synth request
500'd with TypeError.

Fix: `x_vector_only_mode=` → `xvec_only=` (the correct name on
faster_qwen3_tts==0.2.6's higher-level voice-clone API).
`instruct=` was already right.

New tests guard the instructions field, the x-vector fallback,
and the Kokoro protocol-bump compatibility path.

Kokoro slugs (kokoro-82m, kokoro-82m-nvidia) were unaffected by
the v0.6.0 regression.

No breaking change. No new dependency.