fix: Supertonic 3 compatibility across all language examples

- README Quick Start: format `duration[0]` instead of the ndarray itself
  (numpy refuses `f"{ndarray:.2f}"`; matches official `dur[0]:.2f` pattern)
- py/example_pypi.py: print synthesized duration to mirror the docstring example
- Add `"na"` to AVAILABLE_LANGS / Languages.Available / availableLangs
  across all 11 runtimes (Python/Node/Web/Java/C++/C#/Go/Swift/Rust/Flutter/iOS)
  so the language-agnostic fallback advertised in the README actually passes
  per-runtime lang validation before being sent to the v3 ONNX duration predictor

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

py/example_pypi.py

@@ -13,4 +13,5 @@ wav, duration = tts.synthesize(text, voice_style=style)
 # duration: np.ndarray, shape = (1,)
 
 # Save to file
-tts.save_audio(wav, "results/example_pypi.wav")
+tts.save_audio(wav, "results/example_pypi.wav")
+print(f"Generated {duration[0]:.2f}s of audio")