Tokenization Solutions — landing page (solutions/tokenization/index)

**Page:** `solutions/tokenization/index.mdx`

**Context:** Subdirs `ats/`, `nft-studio/`, `stablecoin/` are written.

**Scope:** Overview routing into ATS, NFT Studio, and Stablecoin Studio with brief positioning of each.

### Acceptance criteria
- [ ] Replace the placeholder template with a real landing page
- [ ] Remove `hidden: true` from the frontmatter
- [ ] **No "Browse by section" block** — the side nav covers that; open straight into the deep-dive sections
- [ ] Route into the written sibling pages via ``/``
- [ ] Follow the style guide (markdown tables only; no AI-tell phrasing)

Start with solutions/tokenization/index.mdx and compare the written pages in solutions/tokenization/ats/, nft-studio/, and stablecoin/. Replace the placeholder with an overview that routes to those pages using CardGroup/Card, remove hidden: true, omit a “Browse by section” block, and follow the stated style-guide constraints.

Written by the indexing model from the issue text.