Hedera-Native Features — landing page (evm/hedera-services/index)

**Page:** `evm/hedera-services/index.mdx`

**Context:** Subdirs `hts-solidity/`, `hybrid/`, `system-contracts/` plus `why-use-native-services`.

**Scope:** Overview of calling Hedera services from Solidity via system contracts; route into HTS-from-Solidity, hybrid, and system contracts.

### 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)