ci: Add GitHub Actions workflow for building desktop distributions

This commit introduces a new GitHub Actions workflow (`.github/workflows/build-desktop.yml`) to automate the creation of native desktop application packages.

The workflow is triggered on pushes to version tags (e.g., `v1.0.0`).

It uses a matrix strategy to build for multiple operating systems:
-   **macOS:** Generates a `.dmg` file.
-   **Windows:** Generates an `.msi` file.
-   **Linux (Ubuntu):** Generates a `.deb` file.

Each build job checks out the code, sets up JDK 17, and runs the corresponding Gradle task (`packageDmg`, `packageMsi`, `packageDeb`) to create the native package. The resulting artifact is then uploaded.

Author: Coding-Meet

composeApp/build.gradle.kts

@@ -78,7 +78,7 @@ compose {
         application {
             mainClass = "com.meet.gitbackup.hub.MainKt"
 //            javaHome = System.getenv("JAVA_HOME")
-            javaHome = "/Users/meet/Library/Java/JavaVirtualMachines/ms-17.0.15/Contents/Home"
+//            javaHome = "/Users/meet/Library/Java/JavaVirtualMachines/ms-17.0.15/Contents/Home"
 
             nativeDistributions {
                 targetFormats(