fix(review-gates): green success badges, null-safe preview rows, optional section items

- Extract shared statusBadgeClass() helper (src/viewers/statusBadge.ts) so
  SqlViewer, CteResultViewer and PhaseSummaryViewer can't drift: ok/success/
  passed/promoted render green (--success), warn renders amber (--warning),
  error/failed stay destructive red, everything else stays neutral outline.
  Previously CteResultViewer/PhaseSummaryViewer mapped "ok"/"promoted" to the
  default badge variant, which is bg-primary (GSD red) — success states
  rendered red.
- enrich.js: buildCteResultV2 now falls back preview.rows to [] instead of
  null when last_test.preview_rows is missing (pre-upgrade ok records), and
  CteResultViewer reads result.preview?.rows?.length with a null-safe
  fallback so it degrades to the "No preview rows" empty state instead of
  crashing.
- PhaseSummaryViewer: section.items is optional (model-authored sections can
  be prose-only); render (section.items ?? []) instead of crashing.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

harness/.pi/extensions/gate/__tests__/enrich.test.js

@@ -132,6 +132,15 @@ test("buildCteResultV2 builds preview from last_test.columns/preview_rows", () =
   assert.deepEqual(out.warnings, []);
 });
 
+test("buildCteResultV2: last_test.preview_rows null (pre-upgrade ok records) -> preview.rows is []", () => {
+  const cteInfo = {
+    name: "a", index: 1, total: 1, sql: "WITH a AS (SELECT 1)", doc: null,
+    last_test: { status: "ok", execution_ms: 1, row_sample: 1, warnings: [], sql_hash: "h", columns: ["cod_paz"], preview_rows: null },
+  };
+  const out = buildCteResultV2({ schema_version: 2 }, cteInfo);
+  assert.deepEqual(out.preview.rows, []);
+});
+
 test("buildCteResultV2: columns[] carries name, with description left as an empty placeholder (filled separately by the gate)", () => {
   const cteInfo = {
     name: "a", index: 1, total: 1, sql: "WITH a AS (SELECT 1)", doc: null,

harness/.pi/extensions/gate/enrich.js

@@ -85,7 +85,7 @@ function buildCteResultV2(thinData, cteInfo) {
 		warnings: lt.warnings || [],
 		sql_hash: lt.sql_hash,
 		columns: (lt.columns || []).map((name) => ({ name, description: "" })),
-		preview: { columns: lt.columns || [], rows: lt.preview_rows || null },
+		preview: { columns: lt.columns || [], rows: lt.preview_rows || [] },
 		note: thin.note,
 	};
 }