initial: Kotlin/Gradle skeleton for cloud-installer

Compiles to a 3.4 MB fat jar via shadow plugin.
Entrypoint with CLI dispatch (pull/push subcommands) + FlatLaf init.
Real sync logic stubbed; lands in subsequent commits per task plan.

Build via containerized gradle (8.10.2 + jdk21) to sidestep the
Kotlin 2.1 + JDK 26 compiler crash. Documented in README.

CI workflow tags-only release artifact upload prepared (needs
RELEASE_TOKEN secret in repo settings before first tag).

src/main/kotlin/center/timemachine/cloud/Cli.kt

@@ -0,0 +1,20 @@
+package center.timemachine.cloud
+
+/**
+ * Subcommand dispatchers. Skeleton — real arg parsing + sync logic lands
+ * in subsequent tasks. For now these print intent and exit cleanly so the
+ * fat jar can be smoke-tested end-to-end through Prism / frazclient.
+ */
+object Cli {
+    fun runPull(args: Array<String>): Int {
+        println("cloud-installer pull: ${args.joinToString(" ")}")
+        println("(not yet implemented; skeleton commit only)")
+        return 0
+    }
+
+    fun runPush(args: Array<String>): Int {
+        println("cloud-installer push: ${args.joinToString(" ")}")
+        println("(not yet implemented; skeleton commit only)")
+        return 0
+    }
+}

src/main/kotlin/center/timemachine/cloud/Main.kt

@@ -0,0 +1,74 @@
+package center.timemachine.cloud
+
+import com.formdev.flatlaf.themes.FlatMacDarkLaf
+import javax.swing.UIManager
+
+/**
+ * cloud-installer entrypoint.
+ *
+ * Invoked twice in the launcher hooks:
+ *   PreLaunch:  java -jar cloud-installer.jar pull  --url=... --pack-folder=...
+ *   PostExit:   java -jar cloud-installer.jar push  --url=... --pack-folder=...
+ *
+ * Exit codes:
+ *   0  ok
+ *   1  user cancelled
+ *   2  error
+ */
+fun main(args: Array<String>) {
+    if (args.isEmpty() || args[0] in listOf("-h", "--help", "help")) {
+        printHelp()
+        return
+    }
+    if (args[0] in listOf("--version", "-V")) {
+        println("cloud-installer 0.1.0")
+        return
+    }
+
+    // Install FlatLaf theme as early as possible so any Swing window
+    // we open later picks it up. Falls back to system L&F on failure.
+    try {
+        UIManager.setLookAndFeel(FlatMacDarkLaf())
+    } catch (e: Exception) {
+        System.err.println("note: FlatLaf init failed (${e.message}); using system L&F")
+    }
+
+    val subcommand = args[0]
+    val rest = args.drop(1).toTypedArray()
+
+    val rc = when (subcommand) {
+        "pull" -> Cli.runPull(rest)
+        "push" -> Cli.runPush(rest)
+        else -> {
+            System.err.println("unknown subcommand: $subcommand")
+            printHelp()
+            2
+        }
+    }
+    kotlin.system.exitProcess(rc)
+}
+
+private fun printHelp() {
+    println("""
+        cloud-installer — per-user state sync for Minecraft clients
+
+        Usage:
+          java -jar cloud-installer.jar <subcommand> [flags]
+
+        Subcommands:
+          pull     Fetch user's cloud state, apply conflict resolution, write to instance.
+          push     Walk instance, build snapshot, upload changed files.
+
+        Flags:
+          --url <URL>           cloud-svc base URL (required)
+          --pack-folder <DIR>   instance dir to sync into/from (default: ".")
+          --token <STR>         bearer token (or use --token-file)
+          --token-file <PATH>   read token from this file (default: <pack-folder>/.cloud-token)
+          -g, --no-gui          headless mode; conflicts auto-resolve to remote-wins
+          -V, --version         print version
+          -h, --help            print this help
+
+        Environment:
+          CLOUD_TOKEN           fallback token source if no flag and no file
+    """.trimIndent())
+}