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/flatpak/build-flatpak.sh

@@ -2,11 +2,11 @@
 set -euo pipefail
 
 ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
-MANIFEST="$ROOT_DIR/packaging/flatpak/io.orbithub.OrbitHub.yml"
+MANIFEST="$ROOT_DIR/packaging/flatpak/org.darksingularity.OrbitHub.yml"
 DIST_DIR="${1:-$ROOT_DIR/dist/flatpak}"
 BUILD_DIR="$DIST_DIR/build"
 REPO_DIR="$DIST_DIR/repo"
-BUNDLE="$DIST_DIR/io.orbithub.OrbitHub.flatpak"
+BUNDLE="$DIST_DIR/org.darksingularity.OrbitHub.flatpak"
 
 if ! command -v flatpak-builder >/dev/null 2>&1; then
   echo "flatpak-builder is required. Install it first:" >&2
@@ -22,5 +22,5 @@ flatpak-builder \
   "$BUILD_DIR" \
   "$MANIFEST"
 
-flatpak build-bundle "$REPO_DIR" "$BUNDLE" io.orbithub.OrbitHub
+flatpak build-bundle "$REPO_DIR" "$BUNDLE" org.darksingularity.OrbitHub
 echo "Created $BUNDLE"

packaging/flatpak/org.darksingularity.OrbitHub.yml

@@ -1,4 +1,4 @@
-app-id: io.orbithub.OrbitHub
+app-id: org.darksingularity.OrbitHub
 runtime: org.kde.Platform
 runtime-version: "6.10"
 sdk: org.kde.Sdk