feat(settings): comparison-overlay becomes a global dashboard preference

Up to v1.4.21 the comparison-baseline toggle lived in two places: the
canonical Settings → Dashboard picker (where it's persisted) and an
on-surface duplicate above the Daily Briefing on `/insights`. Per the
"no split" rule the duplicate is removed: the toggle is a global
preference, so it belongs in Settings only.

Every chart on `/insights` still consumes the resolved
`comparisonBaseline` from the same dashboard-layout query the picker
writes to, so flipping the Settings toggle keeps propagating to every
overlay on next refetch — only the duplicate UI affordance is gone.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/__tests__/insights-polish.test.ts

@@ -180,3 +180,31 @@ describe("v1.4.19 A3 — chart-token leak hardening", () => {
     expect(parseChartTokens("metric:WEIGHT")).toEqual(["metric:WEIGHT"]);
   });
 });
+
+describe("v1.4.22 A3 — comparison toggle is global Settings only", () => {
+  /**
+   * The comparison-overlay toggle is a global preference. Up to v1.4.21
+   * the toggle existed both in `/settings/dashboard` (canonical) and
+   * `/insights` (via `<DailyBriefing metaSlot={<CompareToggle />} />`).
+   * Per `feedback_settings_no_split.md` the toggle now lives in
+   * Settings only — the on-surface affordance is gone from `/insights`.
+   * Every chart still consumes the resolved `comparisonBaseline` value
+   * the same way it did before, so flipping the Settings toggle still
+   * propagates to the page on next refetch.
+   */
+  it("/insights does NOT mount <CompareToggle /> anywhere", () => {
+    const src = load(INSIGHTS_PATH);
+    expect(src).not.toMatch(/<CompareToggle\b/);
+    expect(src).not.toMatch(
+      /from\s+["']@\/components\/comparison\/compare-toggle["']/,
+    );
+  });
+
+  it("/insights still consumes the resolved comparisonBaseline (only the UI is gone)", () => {
+    // Drift guard — the page must still hand `compareBaseline` to every
+    // chart so the global Settings toggle keeps driving the overlay.
+    const src = load(INSIGHTS_PATH);
+    expect(src).toContain("comparisonBaseline");
+    expect(src).toContain("compareBaseline");
+  });
+});

src/app/insights/page.tsx

@@ -49,7 +49,6 @@ import { CorrelationRow } from "@/components/insights/correlation-row";
 import { useInsightsAdvisorQuery } from "@/components/insights/use-insights-advisor";
 import type { CorrelationResult } from "@/lib/insights/correlations";
 import { toWeekISO } from "@/lib/insights/week-iso";
-import { CompareToggle } from "@/components/comparison/compare-toggle";
 // Recharts is ~108 KiB Brotli — defer-load it via a self-contained scatter
 // wrapper so the bundle only lands once a correlation card actually renders.
 // Every scatter card sits inside a `length >= 5` gate and below the fold,
@@ -979,7 +978,6 @@ export default function InsightsPage() {
         loading={advisor.isLoading}
         onRegenerate={advisor.regenerate}
         regenerating={advisor.isRegenerating}
-        metaSlot={<CompareToggle />}
       />
 
       {/* v1.4.20 phase B3 — Correlation discovery row. Three pre-defined