Implements automatic registration of URI schemes with the Windows
Registry, enabling users to click custom links (e.g., fiji://open)
in browsers or other applications to launch the Java application.

Key components:
- SchemeInstaller interface for platform-independent scheme registration
- WindowsSchemeInstaller using Windows reg commands (no JNA dependency)
- LinkHandler.getSchemes() for handlers to declare supported schemes
- DefaultLinkService auto-registers schemes on context initialization

The launcher sets the scijava.app.executable system property to
specify the executable path for registration.

Registration uses HKEY_CURRENT_USER and requires no admin privileges.
Includes comprehensive tests and documentation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

"URI scheme" is more technically correct.

According to RFC 3986 (the URI specification), "scheme" is formally part
of URI syntax, and the official IANA registry is called "Uniform
Resource Identifier (URI) Schemes".

The distinction:
- URI = Broader term for identifying resources
- URL = Specific type of URI that includes location/access information

Custom schemes like myapp://open/file are technically URIs, and the
myapp part is a "URI scheme". While "URL scheme" is used colloquially
(especially in mobile app contexts), "URI scheme" is more precise.

Extends URI scheme registration to Linux via .desktop file manipulation.
The LinuxSchemeInstaller modifies the MimeType field in the .desktop file
to add x-scheme-handler entries, then registers them using xdg-mime.

Key components:
- DesktopFile: Simple parser/writer for .desktop files
- LinuxSchemeInstaller: Adds URI schemes to existing .desktop files
- Updates DefaultLinkService to support both Windows and Linux

The .desktop file path is specified via the scijava.app.desktop-file
system property.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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