Quickstart — landing page (evm/quickstart/index)

**Page:** `evm/quickstart/index.mdx`

**Context:** Siblings already written — `deploy-with-hardhat`, `deploy-with-foundry`, `deploy-with-remix`, `deploy-with-contract-builder`, `setup-metamask`, `get-test-hbar`, `evm-compatibility-overview`.

**Scope:** Minimal landing that routes users into the deploy paths.

### 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)