feat: config crate with legacy env names

crates/config/src/image_conversion_config.rs

@@ -0,0 +1,11 @@
+use serde::Deserialize;
+
+use crate::lenient;
+
+#[derive(Debug, Clone, Default, Deserialize)]
+#[serde(default)]
+pub struct ImageConversionConfig {
+    #[serde(deserialize_with = "lenient::true_only")]
+    pub enabled: bool,
+    pub format: Option<String>,
+}