Home: Stories widget

### Goal

Implement the **Stories** widget for the Home dashboard using the backend endpoint at `/api/alby/stories`. Integrate the Home Stories strip with a YouTube dialog, optional modal CTAs by story `kind`, and a preview fallback when the API errors.

### Related pull requests

- PR [#2172](https://github.com/getAlby/hub/pull/2172) — `/api/alby/stories` for HTTP + Wails, Home Stories strip with YouTube dialog, optional modal CTAs by story `kind`, preview fallback when the API errors.
- PR [#2175](https://github.com/getAlby/hub/pull/2175) — **Remove Alby Go + extension cards** — drop dedicated Home cards now covered by Stories (or elsewhere).
- PR [#2176](https://github.com/getAlby/hub/pull/2176) — **Remove What’s New card** — same cleanup pass on Home.

### Related

- Epic: #2177
- Prior art: #1650 (superseded by the approach in #2172)

### Done when

- Stories and any embedded media use stable APIs and CSP-safe embedding where needed.