feat(cli): use unified @graphprotocol/gnd package

Replace the `graph node install` GitHub-release downloader with a direct
dependency on `@graphprotocol/gnd`, the unified npm wrapper now published
from the graph-node repo. The wrapper declares the five platform-specific
binary packages as its own optional dependencies, so `pnpm install` of
graph-cli automatically resolves the correct binary for the host and
exposes a `gnd` launcher on `node_modules/.bin`.

The `graph node install` command, its `local-node.ts` GitHub downloader,
and the `commands/node.ts` oclif command all become dead code and are
removed.

Author: lutter

packages/cli/CLAUDE.md

@@ -35,7 +35,6 @@ src/
 | `remove` | Remove data source from manifest |
 | `auth` | Set deploy key |
 | `local` | Manage local Graph Node |
-| `node` | Node operations |
 | `clean` | Remove build artifacts |
 
 ## Protocol System

packages/cli/package.json

@@ -37,6 +37,7 @@
   },
   "dependencies": {
     "@float-capital/float-subgraph-uncrashable": "0.0.0-internal-testing.5",
+    "@graphprotocol/gnd": "^0.43.0",
     "@oclif/core": "4.5.5",
     "@oclif/plugin-autocomplete": "^3.2.11",
     "@oclif/plugin-not-found": "^3.2.29",