feat: implement backup system with compression and bundling

- Add zstd-jni dependency for compression support
- Define Backup record with name, key, incremental, and size fields
- Implement BackupManager with backup listing, deletion, and creation methods
- Create BackupWorker to handle backup operations with server state coordination
- Refactor WorldDir to simplify dimension handling and file listing
- Introduce bundling system with SerialBundlerReader^[[1;5P/Writer for efficient storage
- Add BackupStrategy interface with LocalBackupStrategy implementation
- Support both compressed and uncompressed backup formats
- Add config option for parallel backup operations
- Remove old backup implementation from JustBackupMod
- Update backup file format with metadata footer and magic number validation

src/main/java/io/ib67/sfcraft/BackupWorker.java

@@ -0,0 +1,45 @@
+package io.ib67.sfcraft;
+
+import io.ib67.sfcraft.mixin.LevelStorageAccessor;
+import io.ib67.sfcraft.strategy.BackupStrategy;
+import lombok.SneakyThrows;
+import lombok.extern.log4j.Log4j2;
+import net.minecraft.server.MinecraftServer;
+
+import java.nio.file.Path;
+
+import static io.ib67.sfcraft.JustBackupMod.PERFORMING_BACKUP;
+
+@Log4j2
+public record BackupWorker(
+        MinecraftServer server,
+        BackupManager manager
+) implements Runnable {
+
+    @Override
+    @SneakyThrows
+    public void run() {
+        if (server == null) {
+            log.warn("MinecraftServer is not initialized yet, not doing backup");
+            return;
+        }
+        int i = 0;
+        while (!PERFORMING_BACKUP.compareAndSet(false, true)) {
+            if (i++ % 10 == 0) log.info("Server is saving world while performing backup! waiting...");
+            Thread.sleep(2000);
+        }
+        // performing backup is now true
+        try {
+            if (i == 0) {
+                // not saved yet.
+                server.saveAll(true, true, false);
+            }
+            var session = ((LevelStorageAccessor) server).getSession();
+            var path = session.getDirectory().getRootPath();
+            manager.performBackup();
+            strategy.createBackup(new WorldDir(Path.of(path)));
+        } finally {
+            PERFORMING_BACKUP.set(false);
+        }
+    }
+}