fix(graphql): pin into-stream to v6 so the pkg build works on Node 20

[mgrabina]

Problem

core/build.rs builds the embedded GraphQL server with @yao-pkg/pkg at compile time. pkg does require("into-stream") (CommonJS), but into-stream >= 7 is ESM-only, so on Node 20+ the build fails:

Error [ERR_REQUIRE_ESM]: require() of ES Module .../into-stream/index.js
from .../@yao-pkg/pkg/lib-es5/producer.js not supported.

Because build.rs runs this during cargo build, it breaks the build for every rindexer consumer on a current Node — not just users of the embedded GraphQL server. The committed graphql/package-lock.json even resolves into-stream to 9.x, so npm ci hits it too. Bumping @yao-pkg/pkg to latest does not help (it still require()s into-stream).

Fix

Pin into-stream to 6 (its last CommonJS release) via an npm overrides in graphql/package.json, and regenerate graphql/package-lock.json. pkg can require() a CommonJS module fine.

Verified

• npm run build (the exact pkg invocation from build.rs) now produces the binary instead of crashing with ERR_REQUIRE_ESM.
• A downstream Rust backend compiles against rindexer 0.40 end to end — cargo build runs the graphql build successfully with no skip flag or workaround.

The same issue exists upstream in joshstevens19/rindexer; a matching override there keeps future fork syncs clean.

[linear-code]

SDK-888