fix(telegram-desktop): point Exec at the real binary to stop duplicate launcher icons

Telegram's own Linux runtime checks whether the installed .desktop file's
Exec matches its actual binary path, and silently writes a private copy to
~/.local/share/applications with a randomized name whenever it doesn't.
Our desktop entry pointed at the /usr/bin/telegram-desktop symlink, which
never matched /opt/telegram-desktop/Telegram, so Telegram regenerated a
shadow launcher on every start, producing a second, unmatched icon.

Exec/TryExec now point directly at the installed binary so Telegram's own
check finds a match. Bumped release and updated the checksum for the
changed desktop file.

telegram-desktop/org.telegram.desktop.desktop

@@ -1,8 +1,8 @@
 [Desktop Entry]
 Name=Telegram
 Comment=New era of messaging
-TryExec=telegram-desktop
-Exec=telegram-desktop -- %U
+TryExec=/opt/telegram-desktop/Telegram
+Exec=/opt/telegram-desktop/Telegram -- %U
 Icon=org.telegram.desktop
 Terminal=false
 StartupWMClass=TelegramDesktop
@@ -17,6 +17,6 @@ X-GNOME-UsesNotifications=true
 X-GNOME-SingleWindow=true
 
 [Desktop Action quit]
-Exec=telegram-desktop -quit
+Exec=/opt/telegram-desktop/Telegram -quit
 Name=Quit Telegram
 Icon=application-exit