packaging: rename app ID to org.darksingularity.OrbitHub

The reverse-DNS app ID should reflect a domain we actually control.
Renames the desktop file, AppStream metainfo, icon, Flatpak manifest,
and macOS bundle identifier from io.orbithub.OrbitHub to
org.darksingularity.OrbitHub. Also fixes a stale homepage URL in the
metainfo file pointing at an old git host.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

packaging/linux/org.darksingularity.OrbitHub.desktop

@@ -5,7 +5,7 @@ Name=OrbitHub
 GenericName=Remote Session Manager
 Comment=Manage SSH and RDP sessions in one native app
 Exec=orbithub
-Icon=io.orbithub.OrbitHub
+Icon=org.darksingularity.OrbitHub
 Terminal=false
 Categories=Network;RemoteAccess;Utility;
 StartupNotify=true

packaging/linux/org.darksingularity.OrbitHub.metainfo.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <component type="desktop-application">
-  <id>io.orbithub.OrbitHub</id>
+  <id>org.darksingularity.OrbitHub</id>
   <name>OrbitHub</name>
   <summary>Unified remote session manager for SSH and RDP</summary>
   <metadata_license>MIT</metadata_license>
@@ -8,8 +8,8 @@
   <description>
     <p>OrbitHub is a native desktop app for organizing connection profiles and launching SSH and RDP sessions in one tabbed interface.</p>
   </description>
-  <launchable type="desktop-id">io.orbithub.OrbitHub.desktop</launchable>
-  <url type="homepage">https://git.firebugit.com/ksmith/orbithub</url>
+  <launchable type="desktop-id">org.darksingularity.OrbitHub.desktop</launchable>
+  <url type="homepage">https://git.darksingularity.org/DarkSingularity/orbithub</url>
   <provides>
     <binary>orbithub</binary>
   </provides>