fix: inflate the Android splash icon on API 29/30

[KonradIT]

installSplashScreen() threw Resources$NotFoundException before the first frame on every minSdk device: opc_splash_empty was a <vector> carrying only a comment, and VectorDrawable.inflateChildElements rejects a vector with no <path> ("no path defined"). API 31+ draws the splash in the platform and never inflates the icon, so the crash was invisible above API 30 and to lint and unit tests.

Give the vector one fully transparent path. The hold stays invisible, so the splash still never flashes a square logo.

Crash reproduced on a physical MI_PAD_4 (Android 10, API 29, arm64-v8a).

App works fine on Pixel 10.

What & why

TestFlight notes

Checklist

• just check passes.
• Native production changes: just native-check passes, or the relevant platform check is noted.
• Commits follow Conventional Commits.
• No captures, Wi-Fi passwords, unofficial LUT dumps, signing material, or other secrets.
• Docs/CHANGELOG updated if behavior or setup changed. Public handbook pages updated when protocol, app, or setup visitors read has changed.
• TestFlight-triggering changes include reviewed ios/TestFlight/WhatToTest.en-US.txt copy.
• iOS release PRs: bump MARKETING_VERSION in ios/Config/Version.xcconfig when starting a new version train.