Q‑Blog v0.3.0 — Enhancements

- Image Lightbox: Click images in blog posts to open a full‑window overlay for easier viewing. Close by clicking anywhere or pressing Escape.
- Scroll‑To‑Top Button: A floating button appears after you scroll down and returns you to the top smoothly when clicked.
- Bookmarks: Save links to Q‑Blogs and individual posts. Access saved items from the new Bookmarks menu entry and manage them on the Bookmarks page.
  - On first load, existing Favorites are migrated into Bookmarks automatically and then cleared from the old storage.

Developer Notes

- New components: `src/components/common/ImageLightbox.tsx`, `src/components/common/ScrollToTop.tsx`.
- New slice: `src/state/features/bookmarksSlice.ts` added to `src/state/store.ts`.
- New page: `src/pages/Bookmarks/Bookmarks.tsx` and route `/bookmarks` wired in `src/App.tsx`.
- `BlogIndividualPost` and `BlogIndividualProfile` updated with bookmark toggles.
- `Navbar` now shows Bookmarks (Favorites became Bookmarks). Post list cards now use Bookmarks.
  - The main header now has: Q‑Blog logo, search bar, notifications bell, a Main Menu (Create Blog/Post, My Blogs, view toggle, Subscriptions, Bookmarks, Blocked Names, Q‑Mail), and the Name selector dropdown (for switching names only).
- `ResponsiveImage` now forwards `alt` to the underlying `<img>` for improved a11y.