Resolve dedup + write 'The Graph' (evm/integrations/indexing/the-graph)

**Page:** `evm/integrations/indexing/the-graph.mdx`

⚠️ **Decision needed first:** this likely overlaps `evm/tools/other/the-graph.mdx`. Decide: merge, redirect, or split (tool setup vs integration patterns) **before** authoring.

**Scope (if kept):** deploying a subgraph against Hedera and querying indexed data.

### Acceptance criteria
- [ ] Replace the placeholder template with real content
- [ ] Remove `hidden: true` from the frontmatter
- [ ] Follow the style guide: **markdown tables only** (no HTML ``), and avoid AI-tell phrasing (no em-dashes, "delve", "leverage", "not just X but Y")
- [ ] Add working cross-links to related pages
- [ ] Confirm any code samples run on testnet