standardized JAR naming to gittally.jar (version-free); updated scripts, docs, and build config to align; added --version support via BuildProperties

src/main/kotlin/de/hoennig/gittally/GitTallyCommand.kt

@@ -6,6 +6,8 @@ import de.hoennig.gittally.commands.InitCommand
 import de.hoennig.gittally.commands.RetryCommand
 import de.hoennig.gittally.commands.ServerCommand
 import de.hoennig.gittally.commands.StatusCommand
+import org.springframework.beans.factory.ObjectProvider
+import org.springframework.boot.info.BuildProperties
 import org.springframework.stereotype.Component
 import picocli.CommandLine
 import picocli.CommandLine.Command
@@ -22,8 +24,22 @@ import picocli.CommandLine.Command
         ConfigPrintCommand::class,
     ],
     mixinStandardHelpOptions = true,
+    versionProvider = BuildPropertiesVersionProvider::class,
     description = ["Lightweight, declarative CI/CD system"],
 )
 class GitTallyCommand : Runnable {
     override fun run(): Unit = throw CommandLine.ParameterException(CommandLine(this), "Specify a subcommand")
 }
+
+/**
+ * Feeds `--version` from the Gradle project version via the `build-info`
+ * [BuildProperties] — the same source as the web UI footer, so the version is
+ * declared only in `build.gradle.kts`. Resolved through picocli's Spring factory;
+ * `dev` when running from classes (IDE, tests) where no build info exists.
+ */
+@Component
+class BuildPropertiesVersionProvider(
+    private val buildProperties: ObjectProvider<BuildProperties>,
+) : CommandLine.IVersionProvider {
+    override fun getVersion(): Array<String> = arrayOf("GitTally v${buildProperties.getIfAvailable()?.version ?: "dev"}")
+}