Restructure step R: the app is Starsync (dev.foxyz.starsync)

- Linux app id dev.foxyz.starsync, binary starsync; Windows starsync.exe,
  company foxyz; server starsync-server; Dart package starsync; archives
  starsync-<ver>-*.
- 1.2.x compatibility: watch_together and watch-together-server
  launchers (Linux) / copies (Windows) in the archive; the updater
  accepts both names and relaunches the new binary; update.sh/.bat use
  whichever server exists.
- First start copies (never moves) the old support folder and this
  app's Hive boxes out of ~/Documents into <support>/hive; a marker
  makes it run once; AppDirs is a port; settings schema version with
  ordered migrations.
- Launcher entry dev.foxyz.starsync.desktop; the old one removed.
- Repository name and URLs unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tool/dev_release.sh

@@ -55,7 +55,7 @@ export VERSION="$NEXT-dev.$N"
 echo "building $VERSION (last published: ${LAST:-none})"
 
 "$ROOT/tool/package_linux.sh" --no-upload
-TARBALL="$ROOT/dist/watch-together-$VERSION-linux-x64.tar.gz"
+TARBALL="$ROOT/dist/starsync-$VERSION-linux-x64.tar.gz"
 [[ -f "$TARBALL" ]] || { echo "error: $TARBALL missing" >&2; exit 1; }
 
 NOTES="$(git -C "$ROOT" log -1 --format=%s)"
@@ -90,5 +90,5 @@ cat <<EOF
 
 Published $VERSION. Dev builds pick it up with their next update check.
 A stable install moves onto test builds once: with the app open, run (bash)
-  p=\$(pgrep -xo watch_together) && d=\$(dirname "\$(readlink /proc/\$p/exe)") && t=\$(mktemp -d) && curl -fsSL $BASE_URL/$(basename "$TARBALL") | tar -xz -C "\$t" --strip-components=1 && cp -rf --remove-destination "\$t"/. "\$d"/ && rm -rf "\$t" && echo "Done: restart the app." || echo "Failed: is the app open?"
+  p=\$(pgrep -xo 'starsync|watch_together') && d=\$(dirname "\$(readlink /proc/\$p/exe)") && t=\$(mktemp -d) && curl -fsSL $BASE_URL/$(basename "$TARBALL") | tar -xz -C "\$t" --strip-components=1 && cp -rf --remove-destination "\$t"/. "\$d"/ && rm -rf "\$t" && echo "Done: restart the app." || echo "Failed: is the app open?"
 EOF