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>

ios/ExampleiOSApp/TTSService.swift

@@ -35,7 +35,8 @@ final class TTSService {
         case tr = "tr"
         case uk = "uk"
         case vi = "vi"
-        
+        case na = "na"
+
         var displayName: String {
             switch self {
             case .en: return "English"
@@ -69,6 +70,7 @@ final class TTSService {
             case .tr: return "Turkish"
             case .uk: return "Ukrainian"
             case .vi: return "Vietnamese"
+            case .na: return "Auto (language-agnostic)"
             }
         }
     }