feat: enforce output version v1 and add version subcommand

src/render/json.rs

@@ -1,9 +1,18 @@
 use crate::model::PrReviewDocument;
+use crate::OUTPUT_VERSION;
 
 pub fn render_json(doc: &PrReviewDocument) -> anyhow::Result<String> {
     Ok(serde_json::to_string_pretty(doc)?)
 }
 
 pub fn parse_json(input: &str) -> anyhow::Result<PrReviewDocument> {
-    Ok(serde_json::from_str(input)?)
+    let doc: PrReviewDocument = serde_json::from_str(input)?;
+    if doc.version != OUTPUT_VERSION {
+        anyhow::bail!(
+            "unsupported document version: {}, expected {}",
+            doc.version,
+            OUTPUT_VERSION
+        );
+    }
+    Ok(doc)
 }