Arch package: start the service and let the GUI reach the agent

The control socket is now opened to the tsunagi group (unit), the Arch
package enables and starts the service on install, adds the installing user
to the group, restarts a running agent on upgrade, and depends on the
libraries the tray loads at run time. The tray looks for the agent's socket
again on every poll instead of once at start, and a missing indicator
library is reported instead of panicking. Repository URLs unified.

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

dist/deb/build-deb.sh

@@ -45,6 +45,8 @@ if [ -n "$tray" ]; then
     # The GUI package is a superset of the headless one and must not coexist
     # with it (both ship /usr/bin/tsunagi).
     extra_control=$'Conflicts: tsunagi\nReplaces: tsunagi\nProvides: tsunagi\n'
+    # What the tray and its window load at run time.
+    extra_control+=$'Depends: libgtk-3-0 | libgtk-3-0t64, libayatana-appindicator3-1 | libappindicator3-1, libxdo3, libxkbcommon0, libwayland-client0, libx11-6, libgl1\n'
     desc_gui=" It also installs the tray GUI (tsunagi-tray) and a desktop launcher so it can be started from the applications menu."
     install -D -m 0755 "$tray" "$root/usr/bin/tsunagi-tray"
     install -D -m 0644 "$here/../linux/tsunagi-tray.desktop" \
@@ -62,7 +64,7 @@ Architecture: ${arch}
 Maintainer: AB <ab@hexor.cy>
 Section: net
 Priority: optional
-Homepage: https://github.com/Ultradesu/tsunagi
+Homepage: https://github.com/house-of-vanity/tsunagi
 ${extra_control}Description: Serverless private mesh networking agent
  tsunagi forms small private mesh IP networks between peers, with NAT
  traversal and no central server. This package installs a static,