Velopack packaging on all platforms with in-app auto-updates

- macOS: .pkg installer replaces the DMG; Linux: .AppImage replaces the ZIP
- winmain runs velopack.App() first (proper hook handling) and checks for
  updates in the background; downloads are applied on next launch
- release.py uploads the vpk update feed (releases.<channel>.json, nupkgs)
  so GiteaSource finds updates on the latest release
- guibuild.py bootstraps a .NET runtime into build/dotnet when the runner
  host lacks one

scripts/release.py

@@ -67,10 +67,12 @@ def load_token() -> str:
 # ZIP + dist helpers
 # ---------------------------------------------------------------------------
 
-# Matches MediaHive-1.2.3-win64.zip, MediaHive-1.2.3-win64-setup.exe,
-# MediaHive-1.2.3-macos-arm64.dmg, etc.
-# Rejects dev/dirty versions like MediaHive-1.2.3.dev0+gabcd-win64.zip
-_CLEAN_ARTIFACT_RE = re.compile(r"^MediaHive-(\d+(?:\.\d+)*)-([A-Za-z0-9._-]+)\.(?:zip|dmg|exe)$")
+# Matches MediaHive-1.2.3-win64-portable.zip, MediaHive-1.2.3-win64-setup.exe,
+# MediaHive-1.2.3-macos-arm64-setup.pkg, MediaHive-1.2.3-linux-x64.AppImage, etc.
+# Rejects dev/dirty versions like MediaHive-1.2.3.dev0+gabcd-win64-portable.zip
+_CLEAN_ARTIFACT_RE = re.compile(
+    r"^MediaHive-(\d+(?:\.\d+)*)-([A-Za-z0-9._-]+)\.(?:zip|dmg|exe|pkg|AppImage)$"
+)
 
 
 def find_releasable_artifacts() -> list[tuple[Path, str, str]]:
@@ -113,6 +115,21 @@ def find_dist_files(version: str) -> list[Path]:
     return [wheel, sdist]
 
 
+def find_velopack_feed_files() -> list[Path]:
+    """Velopack update feed files produced by vpk pack in build/velopack/.
+
+    These keep their original names — the feed JSONs reference them — and
+    in-app updates (GiteaSource) download them from the latest release.
+    """
+    releases_dir = REPO_ROOT / "build" / "velopack"
+    if not releases_dir.exists():
+        return []
+    files: list[Path] = []
+    for pattern in ("RELEASES", "releases.*.json", "assets.*.json", "*.nupkg"):
+        files.extend(sorted(releases_dir.glob(pattern)))
+    return files
+
+
 # ---------------------------------------------------------------------------
 # Gitea API helpers
 # ---------------------------------------------------------------------------
@@ -266,6 +283,13 @@ def main() -> None:
                     continue
                 print(f"Uploading platform artifact: {platform_tag}")
                 upload_asset(client, base_url, repo, release_id, artifact_path)
+                uploaded.add(artifact_path.name)
+                for feed_file in find_velopack_feed_files():
+                    if feed_file.name in uploaded:
+                        print(f"Skipping {feed_file.name}, already on the release.")
+                        continue
+                    upload_asset(client, base_url, repo, release_id, feed_file)
+                    uploaded.add(feed_file.name)
                 print(f"  ✓ {tag} published")
 
         print("\nDone. To publish to PyPI, run:")