feat(cli): kebab eval variants <run_id> — 변형 일관성 진단 리포트

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

crates/kebab-cli/src/main.rs

@@ -422,6 +422,14 @@ enum EvalWhat {
     /// into `eval_runs.aggregate_json` (P5-2).
     Aggregate { run_id: String },
 
+    /// Compute variant-consistency metrics for a stored run and print
+    /// a Markdown report (or JSON with `--json`).
+    Variants {
+        run_id: String,
+        #[arg(long)]
+        json: bool,
+    },
+
     /// Diff two stored runs (P5-2). Default output is a Markdown
     /// summary; use `--json` (top-level flag) for the raw report.
     Compare {
@@ -1392,6 +1400,16 @@ fn run(cli: &Cli) -> anyhow::Result<()> {
                     Ok(())
                 }
 
+                EvalWhat::Variants { run_id, json } => {
+                    let rep = kebab_eval::compute_variant_consistency_with_config(&cfg, run_id)?;
+                    if *json {
+                        println!("{}", serde_json::to_string_pretty(&rep)?);
+                    } else {
+                        print!("{}", kebab_eval::render_variants_md(&rep));
+                    }
+                    Ok(())
+                }
+
                 EvalWhat::Compare {
                     run_a,
                     run_b,