chore(release): v1.4.15

Bumps version to 1.4.15 and adds the corresponding CHANGELOG entry
covering backup completeness, achievements UI, onboarding tour,
doctor-report v2, auto-deploy on GHCR push, empty-states sweep,
notification + integration status UI, AI hallucination guardrails,
mobile UX fixes, and the BD-Zielbereich percentage fix.

Includes the formatting drift left over by the v1.4.15 development
phases (Prettier sweep on touched files) and a typecheck fix in
`dashboard-layout.test.ts` so `pnpm typecheck`, `pnpm lint`,
`pnpm format:check`, `pnpm test`, and `pnpm test:integration` all
pass green on the release tag.

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

src/components/settings/__tests__/dashboard-layout-section.test.tsx

@@ -47,10 +47,7 @@ describe("<DashboardLayoutSection> — tile + chart split", () => {
   });
 
   it("renders both column headers in German", () => {
-    const html = render(
-      <DashboardLayoutSection id="dashboard-layout" />,
-      "de",
-    );
+    const html = render(<DashboardLayoutSection id="dashboard-layout" />, "de");
     expect(html).toContain("Kachel");
     expect(html).toContain("Chart");
   });