Add asset download functionality with builder pattern and example

examples/download_asset.rs

@@ -0,0 +1,40 @@
+//! Example: Download an asset from Immich
+
+use immich_sdk::Client;
+use std::fs;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    // Create a client
+    let client = Client::from_url("https://immich.example.com")?.with_api_key("your-api-key");
+
+    // Asset ID to download (replace with a real asset ID)
+    let asset_id = "your-asset-id-here".parse()?;
+
+    // Download the asset
+    println!("Downloading asset...");
+    let bytes = client.assets().download(asset_id).execute().await?;
+
+    // Save to file
+    let output_path = "/path/to/output/photo.jpg";
+    fs::write(output_path, &bytes)?;
+    println!("Saved {} bytes to {}", bytes.len(), output_path);
+
+    // Or download the edited version if available
+    let edited_bytes = client
+        .assets()
+        .download(asset_id)
+        .edited()
+        .execute()
+        .await?;
+
+    let edited_path = "/path/to/output/photo_edited.jpg";
+    fs::write(edited_path, &edited_bytes)?;
+    println!(
+        "Saved edited version {} bytes to {}",
+        edited_bytes.len(),
+        edited_path
+    );
+
+    Ok(())
+}