fix: align comment numbering with review sequence

tests/render_json_tests.rs

@@ -35,6 +35,7 @@ fn model_json_roundtrip() {
             line: Some(10),
             root_comment: CommentItem {
                 id: 100,
+                review_id: Some(1),
                 user: "reviewer".into(),
                 created_at: "2026-04-08T12:00:00Z".into(),
                 path: Some("src/main.rs".into()),

tests/render_markdown_tests.rs

@@ -48,6 +48,7 @@ fn render_markdown_includes_expected_sections_and_preserves_comment_markdown() {
             line: Some(9),
             root_comment: CommentItem {
                 id: 11,
+                review_id: Some(1),
                 user: "bob".into(),
                 created_at: "2026-04-08T11:01:00Z".into(),
                 path: Some("src/main.rs".into()),
@@ -56,6 +57,7 @@ fn render_markdown_includes_expected_sections_and_preserves_comment_markdown() {
             },
             replies: vec![CommentItem {
                 id: 12,
+                review_id: Some(1),
                 user: "alice".into(),
                 created_at: "2026-04-08T11:02:00Z".into(),
                 path: Some("src/main.rs".into()),
@@ -72,10 +74,14 @@ fn render_markdown_includes_expected_sections_and_preserves_comment_markdown() {
     assert!(md.contains("## Commits"));
     assert!(md.contains("## Diff Stat"));
     assert!(md.contains("## Review 1 (COMMENT)"));
-    assert!(md.contains("### Comment 7.1"));
+    assert!(md.contains("### Comment 7.1.1"));
     assert!(md.contains("src/main.rs:9"));
-    assert!(md.contains("### Reply 7.1.1"));
+    assert!(md.contains("### Reply 7.1.1.1"));
     assert!(md.contains("src/main.rs:12"));
+    let review_pos = md.find("## Review 1 (COMMENT)").unwrap();
+    let comment_pos = md.find("### Comment 7.1.1").unwrap();
+    assert!(comment_pos > review_pos);
+    assert!(!md.contains("## Comments (No Review)"));
     assert!(md.contains("````md"));
     assert!(md.contains("```rs\nlet x = 1;\n```"));
     assert!(md.contains("looks good"));
@@ -111,6 +117,7 @@ fn render_markdown_uses_minimal_fence_for_plain_text() {
             line: None,
             root_comment: CommentItem {
                 id: 1,
+                review_id: None,
                 user: "bob".into(),
                 created_at: "2026-04-08T11:00:00Z".into(),
                 path: None,