1.0.39: fix OOM on large-file uploads; use exact reference icon

- WebDavProvider: replace readBytes() with streaming RequestBody
  (Okio sink.writeAll) so large files (1+ GB) upload without
  allocating the full file in heap — fixes PARTIAL sync status
- App icon: replace vector XML with PNG mipmaps generated directly
  from the user-provided reference image at all densities

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/src/main/res/mipmap-xhdpi/ic_launcher.xml

@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
-    <background android:drawable="@drawable/ic_launcher_background"/>
-    <foreground android:drawable="@drawable/ic_launcher_foreground"/>
-</adaptive-icon>

app/src/main/res/mipmap-xhdpi/ic_launcher_round.xml

@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
-    <background android:drawable="@drawable/ic_launcher_background"/>
-    <foreground android:drawable="@drawable/ic_launcher_foreground"/>
-</adaptive-icon>