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>

deploy/starsync.service

@@ -0,0 +1,29 @@
+# Dedicated Starsync server (no display needed).
+# Install: unpack the release tarball to /opt/starsync (the unit only uses
+# the starsync-server binary in it), copy this file to
+# /etc/systemd/system/, then `systemctl enable --now starsync`.
+# An install from before the rename (/opt/watch-together, unit
+# watch-together, ExecStart .../watch-together-server) keeps working
+# unchanged: the archive still ships watch-together-server as a launcher.
+# Flags: --port <n> (default 8080), --secret <password> (empty = open
+# server, anyone who can reach the port can join), --name, --media <file>,
+# --advertise-host <host>, --no-yt-dlp, --yt-dlp-dir <dir>, --config
+# <file.yaml|json>. See README. The server's yt-dlp (for web page links it
+# fetches) is downloaded into the state directory below.
+# Prefer --config with a root-only file over --secret here: unit files and
+# process lists are readable by other users.
+
+[Unit]
+Description=Starsync dedicated server
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+ExecStart=/opt/starsync/starsync-server --port 8080 --secret change-me
+Restart=on-failure
+DynamicUser=true
+StateDirectory=starsync
+NoNewPrivileges=true
+
+[Install]
+WantedBy=multi-user.target