feat(marketing): HoM feature-spotlight X drafts + brand-voice charter (v0.18.0 B)

The Head of Marketing now markets features, not just releases: a default-off
x_feature_spotlight loop periodically spawns the HoM to investigate what shipped
(CHANGELOG, feature flags, docs/map, KB) and draft ONE held marketing post via
propose_feature_spotlight, reviewed in the X post queue.

- New x_feature source (distinct from x_post, fixing panel mislabeling) + a
  panel Feature-spotlight branch.
- brand_voice column on company_goals (migration 061, single head) as the
  CEO-editable voice source, surfaced in Settings and injected into the HoM
  briefing; a VOICE GUIDE baseline in head-marketing.md.
- propose_feature_spotlight verb (HoM-only), mirroring propose_roadmap.

Gated by x_feature_spotlight_enabled (default off; flag-off dormancy proven).
Also fixed two real bugs found mid-build: company_goals API schemas dropped
brand_voice on GET/PUT; the live charter UI is goals-tab.tsx, not the unmounted
company-goals-card.tsx. Full suite green (2935); migration single-head verified.

panel/src/components/dashboard/__tests__/x-post-queue.test.tsx

@@ -71,6 +71,26 @@ describe("XPostQueue", () => {
     expect(screen.getByDisplayValue("RoboCo v0.17.0 just shipped!")).toBeInTheDocument();
   });
 
+  it("renders a feature-spotlight draft with its own label and badge", async () => {
+    listPosts.mockResolvedValueOnce([
+      {
+        task_id: "x-3",
+        source: "x_feature",
+        title: "X feature spotlight: playbooks",
+        status: "pending",
+        body: "Did you know RoboCo curates playbooks from real task runs?",
+        char_count: 60,
+        feature: { slug: "playbooks", title: "Playbook curation" },
+      },
+    ] as XPost[]);
+
+    render(withQueryClient(<XPostQueue />));
+
+    expect(await screen.findByText("Feature spotlight")).toBeInTheDocument();
+    expect(screen.queryByText("Mention reply")).not.toBeInTheDocument();
+    expect(screen.getByText(/Playbook curation/)).toBeInTheDocument();
+  });
+
   it("disables only the row being approved, not every row's Approve", async () => {
     render(withQueryClient(<XPostQueue />));