fix: increase minSdkVersion to 26 for react-native-vad compatibility

react-native-vad requires Android O (API 26) or higher due to
MethodHandle.invoke usage in ONNX runtime dependencies.

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Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

packages/voice-mobile/app.json

@@ -22,6 +22,7 @@
       "bundleIdentifier": "com.moboudra.voicemobile"
     },
     "android": {
+      "minSdkVersion": 26,
       "adaptiveIcon": {
         "backgroundColor": "#E6F4FE",
         "foregroundImage": "./assets/images/android-icon-foreground.png",