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>

web/helper.js

@@ -1,7 +1,7 @@
 import * as ort from 'onnxruntime-web';
 
 // Available languages for multilingual TTS
-export const AVAILABLE_LANGS = ['en', 'ko', 'ja', 'ar', 'bg', 'cs', 'da', 'de', 'el', 'es', 'et', 'fi', 'fr', 'hi', 'hr', 'hu', 'id', 'it', 'lt', 'lv', 'nl', 'pl', 'pt', 'ro', 'ru', 'sk', 'sl', 'sv', 'tr', 'uk', 'vi'];
+export const AVAILABLE_LANGS = ['en', 'ko', 'ja', 'ar', 'bg', 'cs', 'da', 'de', 'el', 'es', 'et', 'fi', 'fr', 'hi', 'hr', 'hu', 'id', 'it', 'lt', 'lv', 'nl', 'pl', 'pt', 'ro', 'ru', 'sk', 'sl', 'sv', 'tr', 'uk', 'vi', 'na'];
 
 export function isValidLang(lang) {
     return AVAILABLE_LANGS.includes(lang);