Initial commit: Terrafier v0.1.0

- Core world model (World, Dimension, Tile, Terrain, Platform)
- NBT reader/writer with full tag support
- Anvil region (.mca) format reader with chunk parsing
- Block palette compression and export
- Biome database with Minecraft 1.21 biomes
- CLI commands: new, import, export, info, render
- GUI application with egui (viewport, tools, undo/redo)
- Noise-based heightmap generation and editing operations

License: GPL-3.0-or-later

cli/src/cmds/export.rs

@@ -0,0 +1,64 @@
+use clap::Args;
+use std::path::Path;
+
+use crate::util::output::{self, OutputFormat};
+use crate::util::{load_world, progress};
+
+#[derive(Args)]
+pub struct ExportArgs {
+    /// Path to Terrafier world directory
+    pub world: String,
+    /// Output directory for Minecraft save
+    #[arg(short, long)]
+    pub output: String,
+    /// Minecraft data version (default: 3954 for 1.21)
+    #[arg(long, default_value = "3954")]
+    pub data_version: i32,
+}
+
+pub fn cmd_export(
+    args: ExportArgs,
+    format: &OutputFormat,
+    dry_run: bool,
+    validate: bool,
+) -> anyhow::Result<()> {
+    let world_path = Path::new(&args.world);
+    log::info!("Exporting world from: {}", world_path.display());
+
+    let world = load_world(world_path)?;
+    terrafier_core::io::export::validate_export(&world)?;
+
+    let tile_count: usize = world.dimensions.iter().map(|d| d.tiles.len()).sum();
+
+    if validate || dry_run {
+        output::print_result(
+            format,
+            &serde_json::json!({
+                "status": "validated",
+                "input": args.world,
+                "output": args.output,
+                "tiles": tile_count,
+            }),
+        );
+        if dry_run {
+            return Ok(());
+        }
+    }
+
+    let bar = progress::new_bar(tile_count as u64, "Exporting...");
+    terrafier_core::io::export::export_to_save(&world, Path::new(&args.output))?;
+    progress::finish_with("Export complete", bar);
+
+    log::info!("World exported to: {}", args.output);
+    output::print_result(
+        format,
+        &serde_json::json!({
+            "status": "exported",
+            "input": args.world,
+            "output": args.output,
+            "tiles": tile_count,
+        }),
+    );
+
+    Ok(())
+}